In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Initialize denominator defaults to 1
[WHAT & HOW]
Variables, used as denominators and maybe not assigned to other values,
should be initialized to non-zero to avoid DIVIDE_BY_ZERO, as reported
by Coverity.
(cherry picked from commit e2c4c6c10542ccfe4a0830bb6c9fd5b177b7bbb7)
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: don't skip expired elements during walk
There is an asymmetry between commit/abort and preparation phase if the
following conditions are met:
1. set is a verdict map ("1.2.3.4 : jump foo")
2. timeouts are enabled
In this case, following sequence is problematic:
1. element E in set S refers to chain C
2. userspace requests removal of set S
3. kernel does a set walk to decrement chain->use count for all elements
from preparation phase
4. kernel does another set walk to remove elements from the commit phase
(or another walk to do a chain->use increment for all elements from
abort phase)
If E has already expired in 1), it will be ignored during list walk, so its use count
won't have been changed.
Then, when set is culled, ->destroy callback will zap the element via
nf_tables_set_elem_destroy(), but this function is only safe for
elements that have been deactivated earlier from the preparation phase:
lack of earlier deactivate removes the element but leaks the chain use
count, which results in a WARN splat when the chain gets removed later,
plus a leak of the nft_chain structure.
Update pipapo_get() not to skip expired elements, otherwise flush
command reports bogus ENOENT errors.
In the Linux kernel, the following vulnerability has been resolved:
afs: Fix merge preference rule failure condition
syzbot reported a lock held when returning to userspace[1]. This is
because if argc is less than 0 and the function returns directly, the held
inode lock is not released.
Fix this by store the error in ret and jump to done to clean up instead of
returning directly.
[dh: Modified Lizhi Xu's original patch to make it honour the error code
from afs_split_string()]
[1]
WARNING: lock held when returning to user space!
6.13.0-rc3-syzkaller-00209-g499551201b5f #0 Not tainted
------------------------------------------------
syz-executor133/5823 is leaving the kernel with locks still held!
1 lock held by syz-executor133/5823:
#0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline]
#0: ffff888071cffc00 (&sb->s_type->i_mutex_key#9){++++}-{4:4}, at: afs_proc_addr_prefs_write+0x2bb/0x14e0 fs/afs/addr_prefs.c:388
In the Linux kernel, the following vulnerability has been resolved:
iomap: avoid avoid truncating 64-bit offset to 32 bits
on 32-bit kernels, iomap_write_delalloc_scan() was inadvertently using a
32-bit position due to folio_next_index() returning an unsigned long.
This could lead to an infinite loop when writing to an xfs filesystem.
In the Linux kernel, the following vulnerability has been resolved:
dm thin: make get_first_thin use rcu-safe list first function
The documentation in rculist.h explains the absence of list_empty_rcu()
and cautions programmers against relying on a list_empty() ->
list_first() sequence in RCU safe code. This is because each of these
functions performs its own READ_ONCE() of the list head. This can lead
to a situation where the list_empty() sees a valid list entry, but the
subsequent list_first() sees a different view of list head state after a
modification.
In the case of dm-thin, this author had a production box crash from a GP
fault in the process_deferred_bios path. This function saw a valid list
head in get_first_thin() but when it subsequently dereferenced that and
turned it into a thin_c, it got the inside of the struct pool, since the
list was now empty and referring to itself. The kernel on which this
occurred printed both a warning about a refcount_t being saturated, and
a UBSAN error for an out-of-bounds cpuid access in the queued spinlock,
prior to the fault itself. When the resulting kdump was examined, it
was possible to see another thread patiently waiting in thin_dtr's
synchronize_rcu.
The thin_dtr call managed to pull the thin_c out of the active thins
list (and have it be the last entry in the active_thins list) at just
the wrong moment which lead to this crash.
Fortunately, the fix here is straight forward. Switch get_first_thin()
function to use list_first_or_null_rcu() which performs just a single
READ_ONCE() and returns NULL if the list is already empty.
This was run against the devicemapper test suite's thin-provisioning
suites for delete and suspend and no regressions were observed.
In the Linux kernel, the following vulnerability has been resolved:
virtio-blk: don't keep queue frozen during system suspend
Commit 4ce6e2db00de ("virtio-blk: Ensure no requests in virtqueues before
deleting vqs.") replaces queue quiesce with queue freeze in virtio-blk's
PM callbacks. And the motivation is to drain inflight IOs before suspending.
block layer's queue freeze looks very handy, but it is also easy to cause
deadlock, such as, any attempt to call into bio_queue_enter() may run into
deadlock if the queue is frozen in current context. There are all kinds
of ->suspend() called in suspend context, so keeping queue frozen in the
whole suspend context isn't one good idea. And Marek reported lockdep
warning[1] caused by virtio-blk's freeze queue in virtblk_freeze().
[1] https://lore.kernel.org/linux-block/ca16370e-d646-4eee-b9cc-87277c89c43c@samsung.com/
Given the motivation is to drain in-flight IOs, it can be done by calling
freeze & unfreeze, meantime restore to previous behavior by keeping queue
quiesced during suspend.
In the Linux kernel, the following vulnerability has been resolved:
net/sctp: Prevent autoclose integer overflow in sctp_association_init()
While by default max_autoclose equals to INT_MAX / HZ, one may set
net.sctp.max_autoclose to UINT_MAX. There is code in
sctp_association_init() that can consequently trigger overflow.
In the Linux kernel, the following vulnerability has been resolved:
selinux: ignore unknown extended permissions
When evaluating extended permissions, ignore unknown permissions instead
of calling BUG(). This commit ensures that future permissions can be
added without interfering with older kernels.