Linux: >> Linux Kernel >> 6.1.144 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
mm: zswap: properly synchronize freeing resources during CPU hotunplug
In zswap_compress() and zswap_decompress(), the per-CPU acomp_ctx of the
current CPU at the beginning of the operation is retrieved and used
throughout. However, since neither preemption nor migration are disabled,
it is possible that the operation continues on a different CPU.
If the original CPU is hotunplugged while the acomp_ctx is still in use,
we run into a UAF bug as some of the resources attached to the acomp_ctx
are freed during hotunplug in zswap_cpu_comp_dead() (i.e.
acomp_ctx.buffer, acomp_ctx.req, or acomp_ctx.acomp).
The problem was introduced in commit 1ec3b5fe6eec ("mm/zswap: move to use
crypto_acomp API for hardware acceleration") when the switch to the
crypto_acomp API was made. Prior to that, the per-CPU crypto_comp was
retrieved using get_cpu_ptr() which disables preemption and makes sure the
CPU cannot go away from under us. Preemption cannot be disabled with the
crypto_acomp API as a sleepable context is needed.
Use the acomp_ctx.mutex to synchronize CPU hotplug callbacks allocating
and freeing resources with compression/decompression paths. Make sure
that acomp_ctx.req is NULL when the resources are freed. In the
compression/decompression paths, check if acomp_ctx.req is NULL after
acquiring the mutex (meaning the CPU was offlined) and retry on the new
CPU.
The initialization of acomp_ctx.mutex is moved from the CPU hotplug
callback to the pool initialization where it belongs (where the mutex is
allocated). In addition to adding clarity, this makes sure that CPU
hotplug cannot reinitialize a mutex that is already locked by
compression/decompression.
Previously a fix was attempted by holding cpus_read_lock() [1]. This
would have caused a potential deadlock as it is possible for code already
holding the lock to fall into reclaim and enter zswap (causing a
deadlock). A fix was also attempted using SRCU for synchronization, but
Johannes pointed out that synchronize_srcu() cannot be used in CPU hotplug
notifiers [2].
Alternative fixes that were considered/attempted and could have worked:
- Refcounting the per-CPU acomp_ctx. This involves complexity in
handling the race between the refcount dropping to zero in
zswap_[de]compress() and the refcount being re-initialized when the
CPU is onlined.
- Disabling migration before getting the per-CPU acomp_ctx [3], but
that's discouraged and is a much bigger hammer than needed, and could
result in subtle performance issues.
[1]https://lkml.kernel.org/20241219212437.2714151-1-yosryahmed@google.com/
[2]https://lkml.kernel.org/20250107074724.1756696-2-yosryahmed@google.com/
[3]https://lkml.kernel.org/20250107222236.2715883-2-yosryahmed@google.com/
[yosryahmed@google.com: remove comment]
CVSS Score
7.8
EPSS Score
0.0
Published
2025-02-10
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)
CVSS Score
5.5
EPSS Score
0.0
Published
2025-02-10
In the Linux kernel, the following vulnerability has been resolved:
gpio: xilinx: Convert gpio_lock to raw spinlock
irq_chip functions may be called in raw spinlock context. Therefore, we
must also use a raw spinlock for our own internal locking.
This fixes the following lockdep splat:
[ 5.349336] =============================
[ 5.353349] [ BUG: Invalid wait context ]
[ 5.357361] 6.13.0-rc5+ #69 Tainted: G W
[ 5.363031] -----------------------------
[ 5.367045] kworker/u17:1/44 is trying to lock:
[ 5.371587] ffffff88018b02c0 (&chip->gpio_lock){....}-{3:3}, at: xgpio_irq_unmask (drivers/gpio/gpio-xilinx.c:433 (discriminator 8))
[ 5.380079] other info that might help us debug this:
[ 5.385138] context-{5:5}
[ 5.387762] 5 locks held by kworker/u17:1/44:
[ 5.392123] #0: ffffff8800014958 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3204)
[ 5.402260] #1: ffffffc082fcbdd8 (deferred_probe_work){+.+.}-{0:0}, at: process_one_work (kernel/workqueue.c:3205)
[ 5.411528] #2: ffffff880172c900 (&dev->mutex){....}-{4:4}, at: __device_attach (drivers/base/dd.c:1006)
[ 5.419929] #3: ffffff88039c8268 (request_class#2){+.+.}-{4:4}, at: __setup_irq (kernel/irq/internals.h:156 kernel/irq/manage.c:1596)
[ 5.428331] #4: ffffff88039c80c8 (lock_class#2){....}-{2:2}, at: __setup_irq (kernel/irq/manage.c:1614)
[ 5.436472] stack backtrace:
[ 5.439359] CPU: 2 UID: 0 PID: 44 Comm: kworker/u17:1 Tainted: G W 6.13.0-rc5+ #69
[ 5.448690] Tainted: [W]=WARN
[ 5.451656] Hardware name: xlnx,zynqmp (DT)
[ 5.455845] Workqueue: events_unbound deferred_probe_work_func
[ 5.461699] Call trace:
[ 5.464147] show_stack+0x18/0x24 C
[ 5.467821] dump_stack_lvl (lib/dump_stack.c:123)
[ 5.471501] dump_stack (lib/dump_stack.c:130)
[ 5.474824] __lock_acquire (kernel/locking/lockdep.c:4828 kernel/locking/lockdep.c:4898 kernel/locking/lockdep.c:5176)
[ 5.478758] lock_acquire (arch/arm64/include/asm/percpu.h:40 kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5851 kernel/locking/lockdep.c:5814)
[ 5.482429] _raw_spin_lock_irqsave (include/linux/spinlock_api_smp.h:111 kernel/locking/spinlock.c:162)
[ 5.486797] xgpio_irq_unmask (drivers/gpio/gpio-xilinx.c:433 (discriminator 8))
[ 5.490737] irq_enable (kernel/irq/internals.h:236 kernel/irq/chip.c:170 kernel/irq/chip.c:439 kernel/irq/chip.c:432 kernel/irq/chip.c:345)
[ 5.494060] __irq_startup (kernel/irq/internals.h:241 kernel/irq/chip.c:180 kernel/irq/chip.c:250)
[ 5.497645] irq_startup (kernel/irq/chip.c:270)
[ 5.501143] __setup_irq (kernel/irq/manage.c:1807)
[ 5.504728] request_threaded_irq (kernel/irq/manage.c:2208)
CVSS Score
5.5
EPSS Score
0.0
Published
2025-02-09
In the Linux kernel, the following vulnerability has been resolved:
eth: bnxt: always recalculate features after XDP clearing, fix null-deref
Recalculate features when XDP is detached.
Before:
# ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp
# ip li set dev eth0 xdp off
# ethtool -k eth0 | grep gro
rx-gro-hw: off [requested on]
After:
# ip li set dev eth0 xdp obj xdp_dummy.bpf.o sec xdp
# ip li set dev eth0 xdp off
# ethtool -k eth0 | grep gro
rx-gro-hw: on
The fact that HW-GRO doesn't get re-enabled automatically is just
a minor annoyance. The real issue is that the features will randomly
come back during another reconfiguration which just happens to invoke
netdev_update_features(). The driver doesn't handle reconfiguring
two things at a time very robustly.
Starting with commit 98ba1d931f61 ("bnxt_en: Fix RSS logic in
__bnxt_reserve_rings()") we only reconfigure the RSS hash table
if the "effective" number of Rx rings has changed. If HW-GRO is
enabled "effective" number of rings is 2x what user sees.
So if we are in the bad state, with HW-GRO re-enablement "pending"
after XDP off, and we lower the rings by / 2 - the HW-GRO rings
doing 2x and the ethtool -L doing / 2 may cancel each other out,
and the:
if (old_rx_rings != bp->hw_resc.resv_rx_rings &&
condition in __bnxt_reserve_rings() will be false.
The RSS map won't get updated, and we'll crash with:
BUG: kernel NULL pointer dereference, address: 0000000000000168
RIP: 0010:__bnxt_hwrm_vnic_set_rss+0x13a/0x1a0
bnxt_hwrm_vnic_rss_cfg_p5+0x47/0x180
__bnxt_setup_vnic_p5+0x58/0x110
bnxt_init_nic+0xb72/0xf50
__bnxt_open_nic+0x40d/0xab0
bnxt_open_nic+0x2b/0x60
ethtool_set_channels+0x18c/0x1d0
As we try to access a freed ring.
The issue is present since XDP support was added, really, but
prior to commit 98ba1d931f61 ("bnxt_en: Fix RSS logic in
__bnxt_reserve_rings()") it wasn't causing major issues.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-31
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
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-31
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix double free of TCP_Server_Info::hostname
When shutting down the server in cifs_put_tcp_session(), cifsd thread
might be reconnecting to multiple DFS targets before it realizes it
should exit the loop, so @server->hostname can't be freed as long as
cifsd thread isn't done. Otherwise the following can happen:
RIP: 0010:__slab_free+0x223/0x3c0
Code: 5e 41 5f c3 cc cc cc cc 4c 89 de 4c 89 cf 44 89 44 24 08 4c 89
1c 24 e8 fb cf 8e 00 44 8b 44 24 08 4c 8b 1c 24 e9 5f fe ff ff <0f>
0b 41 f7 45 08 00 0d 21 00 0f 85 2d ff ff ff e9 1f ff ff ff 80
RSP: 0018:ffffb26180dbfd08 EFLAGS: 00010246
RAX: ffff8ea34728e510 RBX: ffff8ea34728e500 RCX: 0000000000800068
RDX: 0000000000800068 RSI: 0000000000000000 RDI: ffff8ea340042400
RBP: ffffe112041ca380 R08: 0000000000000001 R09: 0000000000000000
R10: 6170732e31303000 R11: 70726f632e786563 R12: ffff8ea34728e500
R13: ffff8ea340042400 R14: ffff8ea34728e500 R15: 0000000000800068
FS: 0000000000000000(0000) GS:ffff8ea66fd80000(0000)
000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc25376080 CR3: 000000012a2ba001 CR4:
PKRU: 55555554
Call Trace:
<TASK>
? show_trace_log_lvl+0x1c4/0x2df
? show_trace_log_lvl+0x1c4/0x2df
? __reconnect_target_unlocked+0x3e/0x160 [cifs]
? __die_body.cold+0x8/0xd
? die+0x2b/0x50
? do_trap+0xce/0x120
? __slab_free+0x223/0x3c0
? do_error_trap+0x65/0x80
? __slab_free+0x223/0x3c0
? exc_invalid_op+0x4e/0x70
? __slab_free+0x223/0x3c0
? asm_exc_invalid_op+0x16/0x20
? __slab_free+0x223/0x3c0
? extract_hostname+0x5c/0xa0 [cifs]
? extract_hostname+0x5c/0xa0 [cifs]
? __kmalloc+0x4b/0x140
__reconnect_target_unlocked+0x3e/0x160 [cifs]
reconnect_dfs_server+0x145/0x430 [cifs]
cifs_handle_standard+0x1ad/0x1d0 [cifs]
cifs_demultiplex_thread+0x592/0x730 [cifs]
? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
kthread+0xdd/0x100
? __pfx_kthread+0x10/0x10
ret_from_fork+0x29/0x50
</TASK>
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-31
In the Linux kernel, the following vulnerability has been resolved:
net: fec: handle page_pool_dev_alloc_pages error
The fec_enet_update_cbd function calls page_pool_dev_alloc_pages but did
not handle the case when it returned NULL. There was a WARN_ON(!new_page)
but it would still proceed to use the NULL pointer and then crash.
This case does seem somewhat rare but when the system is under memory
pressure it can happen. One case where I can duplicate this with some
frequency is when writing over a smbd share to a SATA HDD attached to an
imx6q.
Setting /proc/sys/vm/min_free_kbytes to higher values also seems to solve
the problem for my test case. But it still seems wrong that the fec driver
ignores the memory allocation error and can crash.
This commit handles the allocation error by dropping the current packet.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-31
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (drivetemp) Fix driver producing garbage data when SCSI errors occur
scsi_execute_cmd() function can return both negative (linux codes) and
positive (scsi_cmnd result field) error codes.
Currently the driver just passes error codes of scsi_execute_cmd() to
hwmon core, which is incorrect because hwmon only checks for negative
error codes. This leads to hwmon reporting uninitialized data to
userspace in case of SCSI errors (for example if the disk drive was
disconnected).
This patch checks scsi_execute_cmd() output and returns -EIO if it's
error code is positive.
[groeck: Avoid inline variable declaration for portability]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-21
In the Linux kernel, the following vulnerability has been resolved:
btrfs: avoid NULL pointer dereference if no valid extent tree
[BUG]
Syzbot reported a crash with the following call trace:
BTRFS info (device loop0): scrub: started on devid 1
BUG: kernel NULL pointer dereference, address: 0000000000000208
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 106e70067 P4D 106e70067 PUD 107143067 PMD 0
Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 1 UID: 0 PID: 689 Comm: repro Kdump: loaded Tainted: G O 6.13.0-rc4-custom+ #206
Tainted: [O]=OOT_MODULE
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS unknown 02/02/2022
RIP: 0010:find_first_extent_item+0x26/0x1f0 [btrfs]
Call Trace:
<TASK>
scrub_find_fill_first_stripe+0x13d/0x3b0 [btrfs]
scrub_simple_mirror+0x175/0x260 [btrfs]
scrub_stripe+0x5d4/0x6c0 [btrfs]
scrub_chunk+0xbb/0x170 [btrfs]
scrub_enumerate_chunks+0x2f4/0x5f0 [btrfs]
btrfs_scrub_dev+0x240/0x600 [btrfs]
btrfs_ioctl+0x1dc8/0x2fa0 [btrfs]
? do_sys_openat2+0xa5/0xf0
__x64_sys_ioctl+0x97/0xc0
do_syscall_64+0x4f/0x120
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
[CAUSE]
The reproducer is using a corrupted image where extent tree root is
corrupted, thus forcing to use "rescue=all,ro" mount option to mount the
image.
Then it triggered a scrub, but since scrub relies on extent tree to find
where the data/metadata extents are, scrub_find_fill_first_stripe()
relies on an non-empty extent root.
But unfortunately scrub_find_fill_first_stripe() doesn't really expect
an NULL pointer for extent root, it use extent_root to grab fs_info and
triggered a NULL pointer dereference.
[FIX]
Add an extra check for a valid extent root at the beginning of
scrub_find_fill_first_stripe().
The new error path is introduced by 42437a6386ff ("btrfs: introduce
mount option rescue=ignorebadroots"), but that's pretty old, and later
commit b979547513ff ("btrfs: scrub: introduce helper to find and fill
sector info for a scrub_stripe") changed how we do scrub.
So for kernels older than 6.6, the fix will need manual backport.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-21
In the Linux kernel, the following vulnerability has been resolved:
fs: relax assertions on failure to encode file handles
Encoding file handles is usually performed by a filesystem >encode_fh()
method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and
name_to_handle_at(2) syscall are ready to cope with the possibility
of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that
currently have a WARN_ON() assertion when ->encode_fh() fails.
Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1fa9 ("ovl: support
encoding non-decodable file handles") in v6.6 as the regressing commit,
but this is not accurate.
The aforementioned commit only increases the chances of the assertion
and allows triggering the assertion with the reproducer using overlayfs,
inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and
other reasons of ->encode_fh() failures and more particularly, it was
also possible with the exact same reproducer using overlayfs that is
mounted with options index=on,nfs_export=on also on kernels < v6.6.
Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to
v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-01-19