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.
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: adapt set backend to use GC transaction API
Use the GC transaction API to replace the old and buggy gc API and the
busy mark approach.
No set elements are removed from async garbage collection anymore,
instead the _DEAD bit is set on so the set element is not visible from
lookup path anymore. Async GC enqueues transaction work that might be
aborted and retried later.
rbtree and pipapo set backends does not set on the _DEAD bit from the
sync GC path since this runs in control plane path where mutex is held.
In this case, set elements are deactivated, removed and then released
via RCU callback, sync GC never fails.
In the Linux kernel, the following vulnerability has been resolved:
dm array: fix releasing a faulty array block twice in dm_array_cursor_end
When dm_bm_read_lock() fails due to locking or checksum errors, it
releases the faulty block implicitly while leaving an invalid output
pointer behind. The caller of dm_bm_read_lock() should not operate on
this invalid dm_block pointer, or it will lead to undefined result.
For example, the dm_array_cursor incorrectly caches the invalid pointer
on reading a faulty array block, causing a double release in
dm_array_cursor_end(), then hitting the BUG_ON in dm-bufio cache_put().
Reproduce steps:
1. initialize a cache device
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524288 linear /dev/sdc $262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1
dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
2. wipe the second array block offline
dmsteup remove cache cmeta cdata corig
mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \
2>/dev/null | hexdump -e '1/8 "%u\n"')
ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \
2>/dev/null | hexdump -e '1/8 "%u\n"')
dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock
3. try reopen the cache device
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524288 linear /dev/sdc $262144"
dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
Kernel logs:
(snip)
device-mapper: array: array_block_check failed: blocknr 0 != wanted 10
device-mapper: block manager: array validator check failed for block 10
device-mapper: array: get_ablock failed
device-mapper: cache metadata: dm_array_cursor_next for mapping failed
------------[ cut here ]------------
kernel BUG at drivers/md/dm-bufio.c:638!
Fix by setting the cached block pointer to NULL on errors.
In addition to the reproducer described above, this fix can be
verified using the "array_cursor/damaged" test in dm-unit:
dm-unit run /pdata/array_cursor/damaged --kernel-dir <KERNEL_DIR>