| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE
open_tree(OPEN_TREE_NAMESPACE) creates a new mount namespace from a
copy of the tree at the given path. The caller needs to be privileged
over its current user namespace because the new mount namespace will be
owned by it. It doesn't need to be privileged over the mount namespace
the tree is copied from. An unprivileged user just needs to create a
user namespace first.
The copy follows the rules of a detached bind mount. Without
AT_RECURSIVE only the mount itself is cloned and its children are left
out. With AT_RECURSIVE unbindable mounts are skipped. Both is fine when
the caller has privileges over the source mount namespace because it
could unmount those mounts anyway. Not so for an unprivileged user in
that mount namespace. For them a mount namespace copy is what unshare()
does. copy_mnt_ns() copies everything including unbindable mounts and
lock_mnt_tree() makes sure nothing can be unmounted in the copy. Nothing
that was covered gets revealed.
create_new_namespace() only does the locking and so the covered content
is right there in the new mount namespace:
# mount -t tmpfs none /tmp/otn; mkdir /tmp/otn/covered
# echo hidden > /tmp/otn/covered/under.txt
# mount -t tmpfs none /tmp/otn/covered
uid 1000, after unshare(CLONE_NEWUSER):
fd = open_tree(AT_FDCWD, "/tmp/otn", OPEN_TREE_NAMESPACE);
setns(fd, CLONE_NEWNS);
open("/covered/under.txt", O_RDONLY) -> "hidden"
Covering paths with mounts is how container runtimes mask parts of
/proc and /sys and how admins hide things.
When the caller's user namespace doesn't own the source mount namespace
copy the way unshare() does and refuse a non-recursive copy of a mount
that has anything mounted below the requested directory and copy
unbindable mounts in a recursive copy. A caller that is privileged over
the source mount namespace sees no change. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()
sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a
strong reference under hdev->lock:
hci_dev_lock(hdev);
hcon = hci_conn_hash_lookup_handle(hdev, handle);
...
conn = sco_conn_hold_unless_zero(hcon->sco_data);
hci_dev_unlock(hdev);
but the pointer is cleared from the other side without that lock. When
the last sco_conn reference is dropped, sco_conn_free() ran
conn->hcon->sco_data = NULL;
with no hdev->lock held, so the RX path could read hcon->sco_data and
call kref_get_unless_zero() on an sco_conn that was concurrently freed:
BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160
Write of size 4 by task kworker/u17:0
Workqueue: hci0 hci_rx_work
Call Trace:
sco_conn_hold_unless_zero+0xbe/0x160
sco_recv_scodata+0x13f/0x490
hci_rx_work+0x3af/0x730
kref_get_unless_zero() only guards against a zero refcount, not against
the backing memory already being freed.
Give hcon->sco_data an actual reference on the sco_conn it points to, so
the object cannot be freed while the pointer is still installed, and only
clear and drop it from sco_conn_del(), which runs under hdev->lock (its
callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in
sco_recv_scodata() also takes hdev->lock, so the store and the read are
now serialised: the RX path either observes NULL or a reference that is
guaranteed to stay valid until it drops its own.
sco_conn_add() no longer hands its kref_init() reference to the caller as
the connection's only reference; that initial reference is the one owned
by hcon->sco_data, and callers get their own via sco_conn_hold().
Because the sco_conn can now outlive the socket (the association keeps it
alive until the link goes down), the hci_conn can no longer be dropped
from sco_conn_free() without regressing socket close: closing a connected
SCO socket must still tear the link down. Move hci_conn ownership to the
socket instead: __sco_chan_add() takes an hci_conn reference and it is
released from sco_chan_del() and sco_sock_destruct(), exactly once. The
sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops
consuming one and sco_connect() drops the hci_connect_sco() reference on
every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: Serialize concurrent connect calls
iso_sock_connect() checks the socket state before taking the socket lock
and drops the lock again before setting up a connection. Two callers can
both pass the admission check while the socket is open or bound.
Caller A can copy its destination for route selection, then caller B can
replace the socket destination before A binds or connects the CIS. A
then uses B's destination with the route selected for its own request.
B can also proceed after A attaches a connection and sets BT_CONNECT.
For deferred BIS setup, B can bind a second BIS and overwrite
iso_pi(sk)->conn, leaving the first connection's reference and conn->sk
back-pointer stranded. Concurrent CIS connects can likewise replace the
socket's connection. Later teardown only detaches the current connection,
so a callback on the old connection can race with socket release and
access a freed socket.
KASAN reported:
BUG: KASAN: slab-use-after-free in iso_sock_hold+0xf7/0x1b0
Call Trace:
iso_sock_hold+0xf7/0x1b0
iso_conn_del+0x7b/0x1d0
iso_connect_cfm+0x186/0x16a0
hci_conn_failed+0x154/0x280
hci_abort_conn_sync+0x3dc/0x7d0
hci_cmd_sync_work+0x173/0x300
Allocated by task 121:
sk_alloc+0x2b/0x6d0
bt_sock_alloc+0x29/0x370
iso_sock_alloc.constprop.0+0x19/0x300
iso_sock_create+0x94/0x100
Freed by task 121:
kfree+0x121/0x3c0
__sk_destruct+0x42b/0x540
iso_sock_release+0x29d/0x340
__sock_release+0xa1/0x260
Check admission under the socket lock and mark the connect operation in
progress before publishing its destination. Keep that flag set across
route lookup and connection setup, rejecting another connect with
-EBADFD before it can change the destination or attach a connection.
Clear the flag after either helper returns, including on failure, so a
failed setup can be retried.
A separate flag is needed because the socket lock must be released before
acquiring the HCI device lock, while BT_CONNECT requires an attached
connection. Keep the existing state transitions and the deferred CIS
completion through iso_sock_recvmsg().
Reject an existing socket attachment in __iso_chan_add() before taking
a new reference or publishing either pointer, so every caller preserves
the connection association. Keep the same-socket, same-connection success
case for deferred CIS setup. Reject an attached socket before BIS setup
so a reusable BIS is not claimed before the attachment is rejected.
In CIS setup, reject a different HCI connection before iso_conn_add()
and drop the per-attempt HCI hold directly. An unowned iso_conn may still
carry another reference after detachment, so its destruction cannot be
relied on to release that hold.
iso_listen_bis() creates a fresh PA HCI/ISO pair under the device lock,
so the temporary iso_conn_put() frees the ISO candidate and drops its
HCI hold on rejection. iso_conn_ready() uses a freshly allocated,
unpublished child with no connection, making the socket-side rejection
unreachable. |
| In the Linux kernel, the following vulnerability has been resolved:
riscv: futex: untag the user pointer before the atomic access
access_ok() checks untagged_addr(uaddr), but arch_futex_atomic_op_inuser()
and futex_atomic_cmpxchg_inatomic() hand the raw uaddr to the inline asm
amoswap/amoadd/.../lr.w+sc.w through the "+m" (*uaddr) operand. When the
tagged address ABI is enabled (CONFIG_RISCV_ISA_SUPM, prctl
PR_SET_TAGGED_ADDR_CTRL with PMLEN != 0), those two addresses differ: a
user pointer whose top PMLEN bits hold a tag passes access_ok() after
untagging, but the atomic is then performed on the still-tagged raw
address.
Supervisor-mode data accesses are not subject to the U-mode pointer
masking (that is governed by menvcfg.PMM, which the kernel does not set),
so hardware does not strip the tag for the kernel's own access. With
Sv57 and PMLEN=16 the tag bits overlap the canonical-address bits, so a
tagged pointer can name a canonical kernel virtual address (e.g. in the
linear map) whose untagged form is a valid user address. An unprivileged
process can thus make FUTEX_WAKE_OP perform an atomic read-modify-write on
an arbitrary kernel address, with the matching FUTEX_OP_CMP_* result
serving as a read oracle.
get_user()/put_user()/raw_copy_{to,from}_user() already untag the pointer
after the access_ok() check; do the same in the futex helpers so the
atomic operates on the address that was actually validated. |
| In the Linux kernel, the following vulnerability has been resolved:
riscv: entry: gate shadow call stack reload on sstatus.SPP, not tp
Under CONFIG_SHADOW_CALL_STACK, handle_exception() reloads the kernel
shadow call stack pointer (gp) only when the trap came from userspace.
It made that decision with scs_load_current_if_task_changed, which
compares the trap-time tp (read back from sscratch into s5) against the
current tp:
beq \prev, tp, _skip_scs
scs_load_current
_skip_scs:
tp is a user-writable register. A user task that sets tp to the
linear-map address of its own task_struct (¤t) before trapping
makes the comparison succeed (can achieve by brute force with KASLR
enable under our test), so the kernel skips scs_load_current and
keeps running with the gp that userspace left in place. Under
CONFIG_SHADOW_CALL_STACK gp is the shadow call stack pointer and
load_global_pointer is a no-op, so the compiler-emitted
"sd ra, -8(gp)" / "ld ra, -8(gp)" in every non-leaf function then write
to, and return through, an attacker-controlled address -- an
unprivileged kernel arbitrary-write and control-flow-hijack primitive.
The poisoned gp is saved to task_struct.scs_sp on return, so the reload
is skipped on every subsequent entry as well.
Decide "came from userspace" from the hardware sstatus.SPP bit (already
in s1 at this point) instead of from tp, mirroring the check that
ret_from_exception already uses a few instructions later. SPP is
written by hardware on trap entry and cannot be forged from U-mode.
Legitimate behaviour is unchanged: user entries (SPP=0) reload the task
shadow call stack, nested kernel entries (SPP=1) skip it. |
| In the Linux kernel, the following vulnerability has been resolved:
EDAC/altera: Fix use-after-free in error paths
In both altr_edac_a10_device_add() and altr_portb_setup(), the error path
freed the dci structure before releasing the devres group. Since the managed
single and double bit IRQ handlers use altdev(dci->pvt_info) as their data, an
IRQ firing between freeing dci and unregistering the IRQs could dereference
the freed memory.
Release the devres group first so the managed IRQs are unregistered
before the dci structure is freed. |
| In the Linux kernel, the following vulnerability has been resolved:
HID: steam: Rearrange teardown sequence
This fixes a narrow window during the teardown sequence where callbacks
could still be scheduled during cleanup that would then have a dangling
pointer to the now-freed steam struct.
This also puts work canceling for rumble and mode switch in
steam_unregister, as that shouldn't persist while the client hdev is open. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix xattr replace when multiple xattrs are packed in the same item
If we have a btrfs_dir_item item that packs multiple xattrs and then we
replace the value of one of them (with the setxattr(2) family of syscalls)
with another value of a different size, we end up not having a fully
initialized btrfs_dir_item, resulting in a corruption that the tree
checker will detect at extent buffer writeback time.
This is because in btrfs_setxattr() when we find a btrfs_dir_item with
multiple xattrs (due to the crc32c hash of their name being the same)
we delete one of the xattr items (btrfs_dir_item) and then insert a new
one, but the deletion and insertion results in shifting existing data in
the leaf and therefore when the new value of a xattr has a different size,
the new btrfs_dir_item is placed in a leaf section that was not
initialized and we only copy the value's data and set the value's length
in the new btrfs_dir_item, without setting the name, the name's length,
the key (which must be all zeroes for xattrs), flags (BTRFS_FT_XATTR) and
transaction ID.
The following script reproduces the issue:
$ cat test.sh
#!/bin/bash
DEV=/dev/sdi
MNT=/mnt/sdi
mkfs.btrfs -f $DEV
mount $DEV $MNT
touch $MNT/testfile
# Add two xattrs that, on btrfs, have the same hash (crc32c) for their
# name and therefore are packed into the same btrfs_dir_item.
setfattr -n user.foobar -v 123 $MNT/testfile
setfattr -n user.WvG1c1Td -v qwerty $MNT/testfile
# Verify the xattrs are present.
echo "xattrs before:"
getfattr --absolute-names --dump $MNT/testfile
# Now replace the value of the foobar xattr with a significantly larger
# value.
setfattr -n user.foobar -v abcdefghijklmnopqrstuvwxyz $MNT/testfile
# Check the xattrs have the expected values.
echo "xattrs after:"
getfattr --absolute-names --dump $MNT/testfile
umount $MNT
Running it:
$ ./test.sh
(...)
xattrs before:
# file: /mnt/sdi/testfile
user.WvG1c1Td="qwerty"
user.foobar="123"
xattrs after:
# file: /mnt/sdi/testfile
user.WvG1c1Td="qwerty"
So the "user.foobar" xattr is missing and there was a transaction abort
when unmounting the fs with the following traces in dmesg:
$ dmesg
[869800.159271] BTRFS warning (device sdi): access to eb bytenr 30474240 len 16384 out of range start 16015 len 25964
[869800.159293] ------------[ cut here ]------------
[869800.159296] WARNING: fs/btrfs/extent_io.c:4408 at report_eb_range+0x44/0x60 [btrfs], CPU#8: getfattr/2605179
[869800.168961] Modules linked in: btrfs dm_thin_pool (...)
[869800.190527] CPU: 8 UID: 0 PID: 2605179 Comm: getfattr Tainted: G W 7.3.0-rc3-btrfs-next-244+ #1 PREEMPT(full)
[869800.193726] Tainted: [W]=WARN
[869800.194502] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[869800.197576] RIP: 0010:report_eb_range+0x44/0x60 [btrfs]
[869800.198985] Code: 48 8b 7b 18 (...)
[869800.203531] RSP: 0018:ffffce4541937d58 EFLAGS: 00010246
[869800.204609] RAX: 0000000000000000 RBX: ffff8dde054b8738 RCX: 0000000000000000
[869800.206137] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffc04c92a0
[869800.207645] RBP: 0000000000003e8f R08: 0000000000000000 R09: 3fffffffffefffff
[869800.226175] R10: ffffce4541937a88 R11: 0000000000000003 R12: 000000000000656c
[869800.227594] R13: ffff8dde14be800f R14: 000000000000656c R15: 0000000000000069
[869800.229097] FS: 00007f59023bb780(0000) GS:ffff8de5788ed000(0000) knlGS:0000000000000000
[869800.231137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[869800.232321] CR2: 0000558dc45e6a78 CR3: 0000000765b16004 CR4: 0000000000370ef0
[869800.233783] Call Trace:
[869800.234330] <TASK>
[869800.234791] read_extent_buffer+0x4d/0x100 [btrfs]
[869800.235898] btrfs_listxattr+0x199/0x240 [btrfs]
[869800.236912] vfs_listxattr+0x51/0
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
namespace: don't inherit MNT_UMOUNT in clone_mnt()
MNT_UMOUNT gets raised on a mount that umount_tree() or umount_one() has
taken out of its namespace. It's never cleared. __detach_mounts()
unhooks a mount that carries it instead of unmounting it.
disconnect_mount() lets an unmounted child stay attached only if its
parent carries it. propagate_umount() takes it as the sign that a mount
is going to be unmounted when it decides what else can be unmounted,
where a chain of locked mounts ends and where a for reparenting an
overmount.
clone_mnt() copies the flags of the source and only masks
MNT_INTERNAL_FLAGS which doesn't include MNT_UMOUNT. A mount that was
lazily unmounted but is kept alive by a file descriptor can still be
copied when its root is an nsfs or pidfs file because may_copy_tree()
accepts those before checking whether the source is mounted at all:
mount --bind /proc/self/ns/net /tmp/x
exec 3< /tmp/x
umount -l /tmp/x
mount --bind /proc/self/fd/3 /tmp/y
The mount on /tmp/y is attached to the caller's namespace with
MNT_UMOUNT already set and every copy of it inherits the flag again.
That causes a number of bugs:
- Unlink its mountpoint from a mount namespace where it isn't one.
__detach_mounts() takes it for a mount that was unmounted earlier,
unhooks it from its parent and drops the reference the namespace
holds on it. It stays in the namespace with one reference too few
and as its own parent, so it can't be unmounted through the file
descriptor anymore and the namespace never finds it again. When the
namespace goes away it's leaked and points to a freed struct
mnt_namespace that may_change_propagation() and anon_ns_root() read
on the next propagation change or mount_setattr() through the file
descriptor.
- Make it shared and unmount a peer. trace_transfers() follows the
flag from the peer into it and strips it from its peer group.
- Let a propagated umount reach it. gather_candidates() marks it with
T_UMOUNT_CANDIDATE but never puts it on the candidate list, so the
mark is never cleared and every later propagated umount skips it. If
it's the parent of a locked mount handle_locked() takes it as the
cutoff and commits the locked child that should have stayed and
disconnect_mount() leaves that child attached to it, unmounted under
a mounted parent, which is what disconnect_mount() exists to
prevent. When the namespace goes away umount_tree() visits the child
a second time. And once __detach_mounts() has made it its own parent
reparent() never finds the end of the chain of unmounted parents.
A clone is a new mount that has never been unmounted. Add MNT_UMOUNT
to MNT_INTERNAL_FLAGS so clone_mnt() never copies it. And warn when
umount_tree() reaches a mount that already has it set. |
| In the Linux kernel, the following vulnerability has been resolved:
namespace: reset the old parent's ->overmount in mnt_change_mountpoint()
__umount_mnt() resets ->overmount of the parent when it unmounts the
mount that overmounts it. mnt_change_mountpoint() doesn't. It moves the
mount to its new parent and leaves the old one pointing at it.
For a mount that is moved beneath in attach_recursive_mnt() that doesn't
matter. The new mount has already reset ->overmount of the old parent by
the time the old top mount is moved onto it.
It matters for reparent() though. propagate_umount() moves a surviving
overmount onto the first ancestor that isn't going to be unmounted. The
mount it was taken from is unmounted immediately afterwards. If a file
descriptor keeps that unmounted mount alive ->overmount points at the
moved mount. That's a dangling pointer and UAF as the moved mount is
unmounted and freed.
do_lock_mount() follows ->overmount from the target path under
mount_lock. With a file descriptor on such a mount as the target of a
mount beneath topmost_overmount() walks into the freed mount and
do_lock_mount() takes references on whatever it finds there.
So reset ->overmount of the old parent in mnt_change_mountpoint() the
same way __umount_mnt() does. A mount's ->overmount is then always a
mount that is attached to it. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin
xe_bo_pin_external() and xe_bo_unpin_external() maintain the bo's
pinned_link list membership in xe->pinned.late.external, based on
whether the current call is the outermost pin or the final unpin.
However, the same external bo's pin_count can also be raised and
lowered directly by __xe_pin_fb_vma()/__xe_unpin_fb_vma(), which pin
the bo as a display scanout buffer without going through
xe_bo_pin_external()/xe_bo_unpin_external() at all, and have no
notion of, or ownership over, pinned_link.
If a bo is pinned both externally (e.g. dma-buf export) and as an fb,
and the external unpin happens first, xe_bo_unpin_external() correctly
observes pin_count > 1 and leaves the bo on pinned_link. When the fb
unpin later performs the true last unpin (pin_count 1 -> 0), it never
touches pinned_link, leaving the bo linked on xe->pinned.late.external
indefinitely. Once the bo is subsequently freed, this stale list entry
points into freed memory, corrupting the list and risking a
use-after-free the next time the list is walked or spliced.
The backup object pin/unpin sites in xe_bo_notifier_prepare_pinned()/
xe_bo_notifier_unprepare_pinned() have the same bypass characteristic,
though they never add their bo to a pinned list, so are not affected
by this particular list-corruption issue.
Move the pinned_link removal into xe_bo_account_unpin(), which already
runs on every unpin path (kernel, external, framebuffer, backup
object) right before the true 1 -> 0 pin_count transition. Since
list_del_init() only operates on the node itself, this removal is
list-agnostic and safe to perform regardless of which list (external
or kernel_bo_present) the bo happens to be linked on, or which code
path is performing the final unpin. Drop the now-redundant explicit
list_del_init() calls in xe_bo_unpin_external() and xe_bo_unpin().
v2:
- New patch
v3:
- Rebased on changes to previous patch.
(cherry picked from commit ca58d36a1f93af586ee93b340c9f9fd81312cc01) |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: Reject concurrent BIS listener setup
iso_sock_listen() drops the socket lock before calling iso_listen_bis()
to preserve the hdev->lock ordering. Two concurrent listen() calls on
the same broadcast socket can therefore both observe BT_BOUND. Caller
A can attach connA and release the locks, then caller B can acquire
them and attach connB before A publishes BT_LISTEN.
__iso_chan_add() checks whether connB already has a socket, but not
whether the socket already has a connection. The second attachment
overwrites iso_pi(sk)->conn, leaking the connA reference and leaving
connA->sk intact. Socket teardown follows connB, so later events on
connA can cause a stale socket access.
Recheck BT_BOUND and require iso_pi(sk)->conn to be NULL after taking
both the HCI device and socket locks in iso_listen_bis(). The connection
check also covers the interval between attachment and publication of
BT_LISTEN. Reject a competing setup with -EBADFD through the existing
unlock path before allocating another connection.
A recorded KASAN report from an instrumented kernel shows:
BUG: KASAN: slab-use-after-free in iso_sock_hold+0x119/0x1f0
Call Trace:
iso_sock_hold+0x119/0x1f0
iso_conn_del+0xe4/0x270
hci_disconn_complete_evt+0x351/0x8c0
hci_event_packet+0x71b/0xb20
hci_rx_work+0x293/0x730
Allocated by task 93:
sk_prot_alloc+0x113/0x220
sk_alloc+0x2b/0x6d0
bt_sock_alloc+0x29/0x370
iso_sock_alloc.constprop.0+0x19/0x300
iso_sock_create+0x94/0x100
Freed by task 93:
kfree+0x121/0x3c0
__sk_destruct+0x42b/0x540
iso_sock_release+0x29d/0x340
__sock_release+0xa1/0x260
sock_close+0x10/0x20 |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
With AF_XDP on a striding RQ, mlx5e defers releasing XSK buffers until
an MPWQE is refilled. If XSK allocation then returns -ENOMEM,
actual_wq_head is not advanced and a later NAPI poll retries the same
WQE.
mlx5e_free_rx_mpwqe() leaves each released slot marked as releasable. On
retry it can therefore call xsk_buff_free() again through stale pointers
after the frames have returned to the XSK pool and been reallocated.
Set all skip_release_bitmap bits in the common error path of
mlx5e_xsk_alloc_rx_mpwqe(). This matches mlx5e_alloc_rx_mpwqe(). A
successful allocation already clears the bitmap after replacing every
buffer, so retries become idempotent without changing the success path.
Fault injection forced three consecutive failures for one selected MPWQE.
Both an early allocation failure and a partial 8-of-16-buffer unwind
released the original 16 XSK buffers only once. Each error left a full
bitmap, the following NAPI retry skipped the release, and a later
successful allocation cleared it. A 20-second AF_XDP zero-copy pressure
run exercised 1,575,262 buffer allocation failures without invalid
descriptors, WQE errors, or kernel warnings. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Use active memslots for the per-vCPU MMIO cache
KVM tags the per-vCPU MMIO cache with a memslot generation so that a
memslot update invalidates cached MMIO information. Both the fill and
validation paths use kvm_memslots(), which unconditionally selects address
space 0, even when the vCPU is running in SMM and using address space 1.
Commit 56f17dd3fbc4 ("kvm: x86: fix stale mmio cache bug") added the
memslot generation to the cache key so that a memslot update could not
leave a stale entry valid. When commit 699023e23965 ("KVM: x86: add SMM
to the MMU role, support SMRAM address space") added the SMM address space,
these helpers were not converted to use the active memslots.
Consequently, an update to the SMM memslots can leave an entry from the old
SMM address space apparently valid after the vCPU returns to the normal
address space. A guest can then cause an access to valid RAM at the same
GFN to be returned to userspace as KVM_EXIT_MMIO.
Completing that exit through the VMM's RAM address space writes the backing
page without going through KVM's write-tracking path. If the page backs a
nested EPT table, KVM can continue using shadow translations derived from
the old contents. The WARN_ON_ONCE() in kvm_mmu_write_protect_fault()
catches this invalid cache and memslot combination.
Use the vCPU's active memslots when caching and validating the entry.
Memslot generations are unique across address spaces, so the generation
also distinguishes the normal and SMM views. This matches the MMIO SPTE
cache, which already uses kvm_vcpu_memslots().
On an unpatched current-mainline kernel, a regression test that fills the
cache in SMM and updates only the SMM memslots fails the intended RAM write
and triggers the kvm_mmu_write_protect_fault() warning. With this change,
the same test completes the RAM write without a warning. The x86/smm_test,
set_memory_region_test, and memslot_modification_stress_test selftests also
pass. |
| In the Linux kernel, the following vulnerability has been resolved:
xfs: fix exchange-range-to-eof file size exchange
Norbert Szetei posted a patch containing an incomplete description of a
bug in XFS_IOC_EXCHANGE_RANGE's TO_EOF flag. The bug tricks
exchange-range into modifying a file so that it has shared blocks
starting beyond EOF, which is never allowed because files never have
written data beyond EOF, and you can only share written data blocks.
This is key to all the incorrect behavior that follows.
Eventually I got from Norbert a description of what's going wrong:
> Fair. Here it is with physical block numbers, 4k blocks. peer is the file
> that gets rewritten and file1 is the one that ends up with the flag
> cleared.
>
> Start, nothing shared:
>
> peer size 4096 -> [100]
> file1 size 12288 -> [200] [201] [202]
> donor1 size 4096 -> [300]
> donor2 size 4096 -> [400]
>
> 1. FICLONERANGE peer's block into file1's middle slot:
>
> peer size 4096 -> [100]
> file1 size 12288 -> [200] [100] [202] reflink flag set
> ^^^^^ both files own block 100
>
> 2. XFS_IOC_EXCHANGE_RANGE file1 against donor1, file1_offset 0,
> file2_offset 8192, length 0, TO_EOF. One block is exchanged, and the sizes
> are exchanged with it:
>
> file1 size 4096 -> [200] [100] [300] reflink flag set
> ^^^^^^^^^^^ still owned, now past the size
> donor1 size 12288 -> [202]
>
> file1 says it is one block long while it still owns three. Nothing was
> unmapped. file2_offset is block 2, so this exchange cannot clear a flag.
>
> 3. XFS_IOC_EXCHANGE_RANGE file1 against donor2, both offsets 0, length 4096.
> By i_disk_size this is two one-block files exchanging everything, so
> xmi_can_exchange_reflink_flags() agrees and the flag is cleared:
>
> file1 size 4096 -> [400] [100] [300] reflink flag CLEARED
> donor2 size 4096 -> [200]
>
> Block 100 is still shared with peer.
>
> 4. pwrite(file1, 4096, 4096), which is file1's second slot, block 100.
> xfs_is_cow_inode(file1) is false, so no CoW:
>
> peer size 4096 -> [100] same block, new contents
>
> Block 100 is the only one that matters here. PoC below, it reads a file
> called peer in the current directory. The filesystem needs reflink and
> exchange-range, which mkfs.xfs 7.x turns on by default.
So yes, TO_EOF is screwing up the file size even if it's actually
exchanging the data block correctly. The following is the intended
behavior of XFS_EXCHANGE_RANGE_TO_EOF, as described by its manpage:
"Ignore the length parameter. All bytes in file1_fd from file1_offset
to EOF are moved to file2_fd, and file2's size is set to
(file2_offset+(file1_length-file1_offset)). Meanwhile, all bytes in
file2 from file2_offset to EOF are moved to file1 and file1's size is
set to (file1_offset+(file2_length-file2_offset))."
In other words, if we only exchange a portion of the file data, then we
should only exchange the portion of the file size that relates to the
exchanged data. Unfortunately, the code swaps the ondisk file size and
the incore file sizes, which is incorrect if the caller passes in a
nonzero offset.
Having confused the file sizes, the PoC uses a second exchange-range
call on what looks like a non-reflinked single-block file. Because the
file size is set incorrectly, exchange-range thinks it's exchanging the
full contents of two files and clears the reflink flag on the broken
file. That enables an extending write of the broken file to rewrite the
shared block that's just past EOF. This has become known colloquially
as refluxfs.
Once the file sizes are set correctly, the second exchange-range no
longer thinks that it's doing a full-contents swap, so it won't clear
the reflink flag on either of its file arguments.
Norbert followed up to an earlier version of this patch with a second
complaint about us not handling the i_disk_size state correctly:
> The offsets are bounded against the incore i_size but subtracted from
>
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
tipc: hold a reference to nodes found by link name
tipc_node_find_by_name() returns a node after dropping its RCU read lock
without taking a reference. The LINK_SET, LINK_GET and LINK_RESET_STATS
handlers then lock and access the node, racing with timer-driven cleanup of
a down peer. Generic netlink serialization does not exclude the node
timer.
The following interleaving can leave a handler using a freed node:
CPU 0: find the node under RCU and release the node read lock
CPU 1: tipc_node_timeout() clears the links and unlinks the down node
CPU 1: drop the list and timer references, queuing tipc_node_free()
CPU 0: leave the RCU read-side critical section
CPU 1: complete the grace period and free the node
CPU 0: acquire the node lock through the stale pointer
LINK_SET also uses the node's media address after releasing the node lock,
when passing queued packets to tipc_bearer_xmit().
KASAN on v7.3-rc5 reported:
BUG: KASAN: slab-use-after-free in _raw_read_lock_bh
Write of size 4 at addr ffff88807e06f008 by task poc/92
Call Trace:
_raw_read_lock_bh kernel/locking/spinlock.c:287
tipc_nl_node_set_link net/tipc/node.c:2475
genl_family_rcv_msg_doit net/netlink/genetlink.c:1114
genl_rcv_msg net/netlink/genetlink.c:1209
netlink_rcv_skb net/netlink/af_netlink.c:2575
Allocated by task 0:
tipc_node_create net/tipc/node.c:539
tipc_node_check_dest net/tipc/node.c:1196
tipc_disc_rcv net/tipc/discover.c:252
Freed by task 92:
kfree mm/slub.c:6801
rcu_core kernel/rcu/tree.c:2919
Last potentially related work creation:
__call_rcu_common.constprop.0 kernel/rcu/tree.c:3181
tipc_node_timeout net/tipc/node.c:814
Acquire a reference to the selected node with kref_get_unless_zero() before
leaving RCU, returning NULL if the node has already been released. Release
that reference on every caller exit after the last node access, including
transmission in LINK_SET. Keep the existing link lookup order and locking
so concurrent link removal still takes the existing error paths. |
| In the Linux kernel, the following vulnerability has been resolved:
drop_monitor: fix out-of-bounds write in reset_per_cpu_data()
In reset_per_cpu_data(), al is computed as:
al = sizeof(struct net_dm_alert_msg);
al += dm_hit_limit * sizeof(struct net_dm_drop_point);
al += sizeof(struct nlattr);
skb = genlmsg_new(al, GFP_KERNEL);
...
nla = nla_reserve(skb, NLA_UNSPEC, sizeof(struct net_dm_alert_msg));
...
msg = nla_data(nla);
memset(msg, 0, al);
Because al includes sizeof(struct nlattr) (the 4-byte attribute header),
genlmsg_new() allocates al bytes of tailroom starting at nla.
However, msg points to nla_data(nla), which is located
sizeof(struct nlattr) bytes past nla. Calling memset(msg, 0, al)
therefore writes al bytes starting from msg, exceeding the allocated
buffer by sizeof(struct nlattr) (4 bytes) and corrupting
skb_shared_info.
Fix this by letting al represent only the payload length, allocating
the skb with genlmsg_new(nla_total_size(al), GFP_KERNEL), and zeroing
al bytes from msg. |
| In the Linux kernel, the following vulnerability has been resolved:
HID: alps: fix use-after-free on input2 registration failure
alps_input_configured() stores data->input2 before calling
input_register_device(). If registration fails, input_free_device()
frees the input device but data->input2 still points to the freed memory.
alps_input_configured() calls hid_hw_open() before allocating input2, so
URBs are already active and raw_event can fire during the failure window.
A U1_SP_ABSOLUTE_REPORT_ID report arriving then causes u1_raw_event()
to dereference the freed data->input2 -> use-after-free.
Fix by only storing input2 into drvdata after successful registration
and adding a NULL guard in the raw_event path. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir
bpf_lsm_has_d_inode_locked() makes the verifier rewrite
bpf_[set|remove]_dentry_xattr() to the _locked variants, which assume
that the caller already holds the inode's i_rwsem. The path_unlink and
path_rmdir hooks are listed, but security_path_unlink() and
security_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the
victim inode's i_rwsem, so a sleepable BPF LSM program attached to
either hook mutates the victim's xattrs without the lock held.
Drop the two path hooks from d_inode_locked_hooks so that the verifier
keeps the locking bpf_[set|remove]_dentry_xattr() variants, which take
the lock themselves. |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: remove stale channels from all sessions on teardown
ksmbd_sessions_deregister() removes a connection's channels from other
sessions' channel lists only while conn->binding is still set:
if (conn->binding) {
hash_for_each_safe(sessions_table, ...)
ksmbd_chann_del(conn, sess);
}
conn->binding is a transient flag: it is cleared once a binding
SESSION_SETUP completes, and also by a subsequent non-binding
SESSION_SETUP on the same connection (a reauthentication on a bound
channel, or a new SessionId==0 setup). A connection that has bound a
channel into another session's ksmbd_chann_list and then clears
conn->binding leaves that channel behind when it disconnects: the
channel, whose chann->conn points at the now freed struct ksmbd_conn,
stays on the owner session's list.
When the owning connection later tears down, the second loop
dereferences the stale channel:
xa_for_each(&sess->ksmbd_chann_list, chann_id, chann)
if (chann->conn != conn)
ksmbd_conn_set_exiting(chann->conn); /* freed */
which is a use-after-free write into the freed ksmbd_conn (the same
stale channel is also walked by show_proc_session() through /proc). The
session is leaked as well, because its channel list never empties.
Remove the conn->binding gate so a connection always removes its
channels from every session on teardown. |
