| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
s390/pci: Avoid deadlock between PCI error recovery and mlx5 crdump
Do not block PCI config accesses through pci_cfg_access_lock() when
executing the s390 variant of PCI error recovery: Acquire just
device_lock() instead of pci_dev_lock() as powerpc's EEH and
generig PCI AER processing do.
During error recovery testing a pair of tasks was reported to be hung:
mlx5_core 0000:00:00.1: mlx5_health_try_recover:338:(pid 5553): health recovery flow aborted, PCI reads still not working
INFO: task kmcheck:72 blocked for more than 122 seconds.
Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kmcheck state:D stack:0 pid:72 tgid:72 ppid:2 flags:0x00000000
Call Trace:
[<000000065256f030>] __schedule+0x2a0/0x590
[<000000065256f356>] schedule+0x36/0xe0
[<000000065256f572>] schedule_preempt_disabled+0x22/0x30
[<0000000652570a94>] __mutex_lock.constprop.0+0x484/0x8a8
[<000003ff800673a4>] mlx5_unload_one+0x34/0x58 [mlx5_core]
[<000003ff8006745c>] mlx5_pci_err_detected+0x94/0x140 [mlx5_core]
[<0000000652556c5a>] zpci_event_attempt_error_recovery+0xf2/0x398
[<0000000651b9184a>] __zpci_event_error+0x23a/0x2c0
INFO: task kworker/u1664:6:1514 blocked for more than 122 seconds.
Not tainted 5.14.0-570.12.1.bringup7.el9.s390x #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u1664:6 state:D stack:0 pid:1514 tgid:1514 ppid:2 flags:0x00000000
Workqueue: mlx5_health0000:00:00.0 mlx5_fw_fatal_reporter_err_work [mlx5_core]
Call Trace:
[<000000065256f030>] __schedule+0x2a0/0x590
[<000000065256f356>] schedule+0x36/0xe0
[<0000000652172e28>] pci_wait_cfg+0x80/0xe8
[<0000000652172f94>] pci_cfg_access_lock+0x74/0x88
[<000003ff800916b6>] mlx5_vsc_gw_lock+0x36/0x178 [mlx5_core]
[<000003ff80098824>] mlx5_crdump_collect+0x34/0x1c8 [mlx5_core]
[<000003ff80074b62>] mlx5_fw_fatal_reporter_dump+0x6a/0xe8 [mlx5_core]
[<0000000652512242>] devlink_health_do_dump.part.0+0x82/0x168
[<0000000652513212>] devlink_health_report+0x19a/0x230
[<000003ff80075a12>] mlx5_fw_fatal_reporter_err_work+0xba/0x1b0 [mlx5_core]
No kernel log of the exact same error with an upstream kernel is
available - but the very same deadlock situation can be constructed there,
too:
- task: kmcheck
mlx5_unload_one() tries to acquire devlink lock while the PCI error
recovery code has set pdev->block_cfg_access by way of
pci_cfg_access_lock()
- task: kworker
mlx5_crdump_collect() tries to set block_cfg_access through
pci_cfg_access_lock() while devlink_health_report() had acquired
the devlink lock.
A similar deadlock situation can be reproduced by requesting a
crdump with
> devlink health dump show pci/<BDF> reporter fw_fatal
while PCI error recovery is executed on the same <BDF> physical function
by mlx5_core's pci_error_handlers. On s390 this can be injected with
> zpcictl --reset-fw <BDF>
Tests with this patch failed to reproduce that second deadlock situation,
the devlink command is rejected with "kernel answers: Permission denied" -
and we get a kernel log message of:
mlx5_core 1ed0:00:00.1: mlx5_crdump_collect:50:(pid 254382): crdump: failed to lock vsc gw err -5
because the config read of VSC_SEMAPHORE is rejected by the underlying
hardware.
Two prior attempts to address this issue have been discussed and
ultimately rejected [see link], with the primary argument that s390's
implementation of PCI error recovery is imposing restrictions that
neither powerpc's EEH nor PCI AER handling need. Tests show that PCI
error recovery on s390 is running to completion even without blocking
access to PCI config space. |
| In the Linux kernel, the following vulnerability has been resolved:
mm/memfd: fix information leak in hugetlb folios
When allocating hugetlb folios for memfd, three initialization steps are
missing:
1. Folios are not zeroed, leading to kernel memory disclosure to userspace
2. Folios are not marked uptodate before adding to page cache
3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache()
The memfd allocation path bypasses the normal page fault handler
(hugetlb_no_page) which would handle all of these initialization steps.
This is problematic especially for udmabuf use cases where folios are
pinned and directly accessed by userspace via DMA.
Fix by matching the initialization pattern used in hugetlb_no_page():
- Zero the folio using folio_zero_user() which is optimized for huge pages
- Mark it uptodate with folio_mark_uptodate()
- Take hugetlb_fault_mutex before adding to page cache to prevent races
The folio_zero_user() change also fixes a potential security issue where
uninitialized kernel memory could be disclosed to userspace through read()
or mmap() operations on the memfd. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: btusb: mediatek: Avoid btusb_mtk_claim_iso_intf() NULL deref
In btusb_mtk_setup(), we set `btmtk_data->isopkt_intf` to:
usb_ifnum_to_if(data->udev, MTK_ISO_IFNUM)
That function can return NULL in some cases. Even when it returns
NULL, though, we still go on to call btusb_mtk_claim_iso_intf().
As of commit e9087e828827 ("Bluetooth: btusb: mediatek: Add locks for
usb_driver_claim_interface()"), calling btusb_mtk_claim_iso_intf()
when `btmtk_data->isopkt_intf` is NULL will cause a crash because
we'll end up passing a bad pointer to device_lock(). Prior to that
commit we'd pass the NULL pointer directly to
usb_driver_claim_interface() which would detect it and return an
error, which was handled.
Resolve the crash in btusb_mtk_claim_iso_intf() by adding a NULL check
at the start of the function. This makes the code handle a NULL
`btmtk_data->isopkt_intf` the same way it did before the problematic
commit (just with a slight change to the error message printed). |
| In the Linux kernel, the following vulnerability has been resolved:
ASoC: Intel: avs: Disable periods-elapsed work when closing PCM
avs_dai_fe_shutdown() handles the shutdown procedure for HOST HDAudio
stream while period-elapsed work services its IRQs. As the former
frees the DAI's private context, these two operations shall be
synchronized to avoid slab-use-after-free or worse errors. |
| In the Linux kernel, the following vulnerability has been resolved:
nvmet-fc: move lsop put work to nvmet_fc_ls_req_op
It’s possible for more than one async command to be in flight from
__nvmet_fc_send_ls_req. For each command, a tgtport reference is taken.
In the current code, only one put work item is queued at a time, which
results in a leaked reference.
To fix this, move the work item to the nvmet_fc_ls_req_op struct, which
already tracks all resources related to the command. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_conn: return ERR_PTR instead of NULL when there is no link
hci_connect_sco currently returns NULL when there is no link (i.e. when
hci_conn_link() returns NULL).
sco_connect() expects an ERR_PTR in case of any error (see line 266 in
sco.c). Thus, hcon set as NULL passes through to sco_conn_add(), which
tries to get hcon->hdev, resulting in dereferencing a NULL pointer as
reported by syzkaller.
The same issue exists for iso_connect_cis() calling hci_connect_cis().
Thus, make hci_connect_sco() and hci_connect_cis() return ERR_PTR
instead of NULL. |
| In the Linux kernel, the following vulnerability has been resolved:
most: usb: hdm_probe: Fix calling put_device() before device initialization
The early error path in hdm_probe() can jump to err_free_mdev before
&mdev->dev has been initialized with device_initialize(). Calling
put_device(&mdev->dev) there triggers a device core WARN and ends up
invoking kref_put(&kobj->kref, kobject_release) on an uninitialized
kobject.
In this path the private struct was only kmalloc'ed and the intended
release is effectively kfree(mdev) anyway, so free it directly instead
of calling put_device() on an uninitialized device.
This removes the WARNING and fixes the pre-initialization error path. |
| In the Linux kernel, the following vulnerability has been resolved:
net: netpoll: fix incorrect refcount handling causing incorrect cleanup
commit efa95b01da18 ("netpoll: fix use after free") incorrectly
ignored the refcount and prematurely set dev->npinfo to NULL during
netpoll cleanup, leading to improper behavior and memory leaks.
Scenario causing lack of proper cleanup:
1) A netpoll is associated with a NIC (e.g., eth0) and netdev->npinfo is
allocated, and refcnt = 1
- Keep in mind that npinfo is shared among all netpoll instances. In
this case, there is just one.
2) Another netpoll is also associated with the same NIC and
npinfo->refcnt += 1.
- Now dev->npinfo->refcnt = 2;
- There is just one npinfo associated to the netdev.
3) When the first netpolls goes to clean up:
- The first cleanup succeeds and clears np->dev->npinfo, ignoring
refcnt.
- It basically calls `RCU_INIT_POINTER(np->dev->npinfo, NULL);`
- Set dev->npinfo = NULL, without proper cleanup
- No ->ndo_netpoll_cleanup() is either called
4) Now the second target tries to clean up
- The second cleanup fails because np->dev->npinfo is already NULL.
* In this case, ops->ndo_netpoll_cleanup() was never called, and
the skb pool is not cleaned as well (for the second netpoll
instance)
- This leaks npinfo and skbpool skbs, which is clearly reported by
kmemleak.
Revert commit efa95b01da18 ("netpoll: fix use after free") and adds
clarifying comments emphasizing that npinfo cleanup should only happen
once the refcount reaches zero, ensuring stable and correct netpoll
behavior. |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: ufs: ufs-qcom: Fix UFS OCP issue during UFS power down (PC=3)
According to UFS specifications, the power-off sequence for a UFS device
includes:
- Sending an SSU command with Power_Condition=3 and await a response.
- Asserting RST_N low.
- Turning off REF_CLK.
- Turning off VCC.
- Turning off VCCQ/VCCQ2.
As part of ufs shutdown, after the SSU command completion, asserting
hardware reset (HWRST) triggers the device firmware to wake up and
execute its reset routine. This routine initializes hardware blocks and
takes a few milliseconds to complete. During this time, the ICCQ draws a
large current.
This large ICCQ current may cause issues for the regulator which is
supplying power to UFS, because the turn off request from UFS driver to
the regulator framework will be immediately followed by low power
mode(LPM) request by regulator framework. This is done by framework
because UFS which is the only client is requesting for disable. So if
the rail is still in the process of shutting down while ICCQ exceeds LPM
current thresholds, and LPM mode is activated in hardware during this
state, it may trigger an overcurrent protection (OCP) fault in the
regulator.
To prevent this, a 10ms delay is added after asserting HWRST. This
allows the reset operation to complete while power rails remain active
and in high-power mode.
Currently there is no way for Host to query whether the reset is
completed or not and hence this the delay is based on experiments with
Qualcomm UFS controllers across multiple UFS vendors. |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_tables: always release netdev hooks from notifier
This reverts "netfilter: nf_tables: skip netdev events generated on netns removal".
The problem is that when a veth device is released, the veth release
callback will also queue the peer netns device for removal.
Its possible that the peer netns is also slated for removal. In this
case, the device memory is already released before the pre_exit hook of
the peer netns runs:
BUG: KASAN: slab-use-after-free in nf_hook_entry_head+0x1b8/0x1d0
Read of size 8 at addr ffff88812c0124f0 by task kworker/u8:1/45
Workqueue: netns cleanup_net
Call Trace:
nf_hook_entry_head+0x1b8/0x1d0
__nf_unregister_net_hook+0x76/0x510
nft_netdev_unregister_hooks+0xa0/0x220
__nft_release_hook+0x184/0x490
nf_tables_pre_exit_net+0x12f/0x1b0
..
Order is:
1. First netns is released, veth_dellink() queues peer netns device
for removal
2. peer netns is queued for removal
3. peer netns device is released, unreg event is triggered
4. unreg event is ignored because netns is going down
5. pre_exit hook calls nft_netdev_unregister_hooks but device memory
might be free'd already. |
| In the Linux kernel, the following vulnerability has been resolved:
tty: fix out-of-bounds access in tty_driver_lookup_tty()
When specifying an invalid console= device like console=tty3270,
tty_driver_lookup_tty() returns the tty struct without checking
whether index is a valid number.
To reproduce:
qemu-system-x86_64 -enable-kvm -nographic -serial mon:stdio \
-kernel ../linux-build-x86/arch/x86/boot/bzImage \
-append "console=ttyS0 console=tty3270"
This crashes with:
[ 0.770599] BUG: kernel NULL pointer dereference, address: 00000000000000ef
[ 0.771265] #PF: supervisor read access in kernel mode
[ 0.771773] #PF: error_code(0x0000) - not-present page
[ 0.772609] Oops: 0000 [#1] PREEMPT SMP PTI
[ 0.774878] RIP: 0010:tty_open+0x268/0x6f0
[ 0.784013] chrdev_open+0xbd/0x230
[ 0.784444] ? cdev_device_add+0x80/0x80
[ 0.784920] do_dentry_open+0x1e0/0x410
[ 0.785389] path_openat+0xca9/0x1050
[ 0.785813] do_filp_open+0xaa/0x150
[ 0.786240] file_open_name+0x133/0x1b0
[ 0.786746] filp_open+0x27/0x50
[ 0.787244] console_on_rootfs+0x14/0x4d
[ 0.787800] kernel_init_freeable+0x1e4/0x20d
[ 0.788383] ? rest_init+0xc0/0xc0
[ 0.788881] kernel_init+0x11/0x120
[ 0.789356] ret_from_fork+0x22/0x30 |
| In the Linux kernel, the following vulnerability has been resolved:
x86/CPU/AMD: Add missing terminator for zen5_rdseed_microcode
Running x86_match_min_microcode_rev() on a Zen5 CPU trips up KASAN for an out
of bounds access. |
| In the Linux kernel, the following vulnerability has been resolved:
io_uring/rw: defer fsnotify calls to task context
We can't call these off the kiocb completion as that might be off
soft/hard irq context. Defer the calls to when we process the
task_work for this request. That avoids valid complaints like:
stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc6-syzkaller-00321-g105a36f3694e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_usage_bug kernel/locking/lockdep.c:3961 [inline]
valid_state kernel/locking/lockdep.c:3973 [inline]
mark_lock_irq kernel/locking/lockdep.c:4176 [inline]
mark_lock.part.0.cold+0x18/0xd8 kernel/locking/lockdep.c:4632
mark_lock kernel/locking/lockdep.c:4596 [inline]
mark_usage kernel/locking/lockdep.c:4527 [inline]
__lock_acquire+0x11d9/0x56d0 kernel/locking/lockdep.c:5007
lock_acquire kernel/locking/lockdep.c:5666 [inline]
lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631
__fs_reclaim_acquire mm/page_alloc.c:4674 [inline]
fs_reclaim_acquire+0x115/0x160 mm/page_alloc.c:4688
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:700 [inline]
slab_alloc mm/slab.c:3278 [inline]
__kmem_cache_alloc_lru mm/slab.c:3471 [inline]
kmem_cache_alloc+0x39/0x520 mm/slab.c:3491
fanotify_alloc_fid_event fs/notify/fanotify/fanotify.c:580 [inline]
fanotify_alloc_event fs/notify/fanotify/fanotify.c:813 [inline]
fanotify_handle_event+0x1130/0x3f40 fs/notify/fanotify/fanotify.c:948
send_to_group fs/notify/fsnotify.c:360 [inline]
fsnotify+0xafb/0x1680 fs/notify/fsnotify.c:570
__fsnotify_parent+0x62f/0xa60 fs/notify/fsnotify.c:230
fsnotify_parent include/linux/fsnotify.h:77 [inline]
fsnotify_file include/linux/fsnotify.h:99 [inline]
fsnotify_access include/linux/fsnotify.h:309 [inline]
__io_complete_rw_common+0x485/0x720 io_uring/rw.c:195
io_complete_rw+0x1a/0x1f0 io_uring/rw.c:228
iomap_dio_complete_work fs/iomap/direct-io.c:144 [inline]
iomap_dio_bio_end_io+0x438/0x5e0 fs/iomap/direct-io.c:178
bio_endio+0x5f9/0x780 block/bio.c:1564
req_bio_endio block/blk-mq.c:695 [inline]
blk_update_request+0x3fc/0x1300 block/blk-mq.c:825
scsi_end_request+0x7a/0x9a0 drivers/scsi/scsi_lib.c:541
scsi_io_completion+0x173/0x1f70 drivers/scsi/scsi_lib.c:971
scsi_complete+0x122/0x3b0 drivers/scsi/scsi_lib.c:1438
blk_complete_reqs+0xad/0xe0 block/blk-mq.c:1022
__do_softirq+0x1d3/0x9c6 kernel/softirq.c:571
invoke_softirq kernel/softirq.c:445 [inline]
__irq_exit_rcu+0x123/0x180 kernel/softirq.c:650
irq_exit_rcu+0x5/0x20 kernel/softirq.c:662
common_interrupt+0xa9/0xc0 arch/x86/kernel/irq.c:240 |
| In the Linux kernel, the following vulnerability has been resolved:
drm/msm: Fix GEM free for imported dma-bufs
Imported dma-bufs also have obj->resv != &obj->_resv. So we should
check both this condition in addition to flags for handling the
_NO_SHARE case.
Fixes this splat that was reported with IRIS video playback:
------------[ cut here ]------------
WARNING: CPU: 3 PID: 2040 at drivers/gpu/drm/msm/msm_gem.c:1127 msm_gem_free_object+0x1f8/0x264 [msm]
CPU: 3 UID: 1000 PID: 2040 Comm: .gnome-shell-wr Not tainted 6.17.0-rc7 #1 PREEMPT
pstate: 81400005 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
pc : msm_gem_free_object+0x1f8/0x264 [msm]
lr : msm_gem_free_object+0x138/0x264 [msm]
sp : ffff800092a1bb30
x29: ffff800092a1bb80 x28: ffff800092a1bce8 x27: ffffbc702dbdbe08
x26: 0000000000000008 x25: 0000000000000009 x24: 00000000000000a6
x23: ffff00083c72f850 x22: ffff00083c72f868 x21: ffff00087e69f200
x20: ffff00087e69f330 x19: ffff00084d157ae0 x18: 0000000000000000
x17: 0000000000000000 x16: ffffbc704bd46b80 x15: 0000ffffd0959540
x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
x11: ffffbc702e6cdb48 x10: 0000000000000000 x9 : 000000000000003f
x8 : ffff800092a1ba90 x7 : 0000000000000000 x6 : 0000000000000020
x5 : ffffbc704bd46c40 x4 : fffffdffe102cf60 x3 : 0000000000400032
x2 : 0000000000020000 x1 : ffff00087e6978e8 x0 : ffff00087e6977e8
Call trace:
msm_gem_free_object+0x1f8/0x264 [msm] (P)
drm_gem_object_free+0x1c/0x30 [drm]
drm_gem_object_handle_put_unlocked+0x138/0x150 [drm]
drm_gem_object_release_handle+0x5c/0xcc [drm]
drm_gem_handle_delete+0x68/0xbc [drm]
drm_gem_close_ioctl+0x34/0x40 [drm]
drm_ioctl_kernel+0xc0/0x130 [drm]
drm_ioctl+0x360/0x4e0 [drm]
__arm64_sys_ioctl+0xac/0x104
invoke_syscall+0x48/0x104
el0_svc_common.constprop.0+0x40/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x34/0xec
el0t_64_sync_handler+0xa0/0xe4
el0t_64_sync+0x198/0x19c
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
Patchwork: https://patchwork.freedesktop.org/patch/676273/ |
| In the Linux kernel, the following vulnerability has been resolved:
vhost: vringh: Modify the return value check
The return value of copy_from_iter and copy_to_iter can't be negative,
check whether the copied lengths are equal. |
| In the Linux kernel, the following vulnerability has been resolved:
cpufreq/longhaul: handle NULL policy in longhaul_exit
longhaul_exit() was calling cpufreq_cpu_get(0) without checking
for a NULL policy pointer. On some systems, this could lead to a
NULL dereference and a kernel warning or panic.
This patch adds a check using unlikely() and returns early if the
policy is NULL.
Bugzilla: #219962 |
| In the Linux kernel, the following vulnerability has been resolved:
s390/dcssblk: fix kernel crash with list_add corruption
Commit fb08a1908cb1 ("dax: simplify the dax_device <-> gendisk
association") introduced new logic for gendisk association, requiring
drivers to explicitly call dax_add_host() and dax_remove_host().
For dcssblk driver, some dax_remove_host() calls were missing, e.g. in
device remove path. The commit also broke error handling for out_dax case
in device add path, resulting in an extra put_device() w/o the previous
get_device() in that case.
This lead to stale xarray entries after device add / remove cycles. In the
case when a previously used struct gendisk pointer (xarray index) would be
used again, because blk_alloc_disk() happened to return such a pointer, the
xa_insert() in dax_add_host() would fail and go to out_dax, doing the extra
put_device() in the error path. In combination with an already flawed error
handling in dcssblk (device_register() cleanup), which needs to be
addressed in a separate patch, this resulted in a missing device_del() /
klist_del(), and eventually in the kernel crash with list_add corruption on
a subsequent device_add() / klist_add().
Fix this by adding the missing dax_remove_host() calls, and also move the
put_device() in the error path to restore the previous logic. |
| In the Linux kernel, the following vulnerability has been resolved:
crypto: aspeed - fix double free caused by devm
The clock obtained via devm_clk_get_enabled() is automatically managed
by devres and will be disabled and freed on driver detach. Manually
calling clk_disable_unprepare() in error path and remove function
causes double free.
Remove the manual clock cleanup in both aspeed_acry_probe()'s error
path and aspeed_acry_remove(). |
| In the Linux kernel, the following vulnerability has been resolved:
netpoll: Fix deadlock in memory allocation under spinlock
Fix a AA deadlock in refill_skbs() where memory allocation while holding
skb_pool->lock can trigger a recursive lock acquisition attempt.
The deadlock scenario occurs when the system is under severe memory
pressure:
1. refill_skbs() acquires skb_pool->lock (spinlock)
2. alloc_skb() is called while holding the lock
3. Memory allocator fails and calls slab_out_of_memory()
4. This triggers printk() for the OOM warning
5. The console output path calls netpoll_send_udp()
6. netpoll_send_udp() attempts to acquire the same skb_pool->lock
7. Deadlock: the lock is already held by the same CPU
Call stack:
refill_skbs()
spin_lock_irqsave(&skb_pool->lock) <- lock acquired
__alloc_skb()
kmem_cache_alloc_node_noprof()
slab_out_of_memory()
printk()
console_flush_all()
netpoll_send_udp()
skb_dequeue()
spin_lock_irqsave(&skb_pool->lock) <- deadlock attempt
This bug was exposed by commit 248f6571fd4c51 ("netpoll: Optimize skb
refilling on critical path") which removed refill_skbs() from the
critical path (where nested printk was being deferred), letting nested
printk being called from inside refill_skbs()
Refactor refill_skbs() to never allocate memory while holding
the spinlock.
Another possible solution to fix this problem is protecting the
refill_skbs() from nested printks, basically calling
printk_deferred_{enter,exit}() in refill_skbs(), then, any nested
pr_warn() would be deferred.
I prefer this approach, given I _think_ it might be a good idea to move
the alloc_skb() from GFP_ATOMIC to GFP_KERNEL in the future, so, having
the alloc_skb() outside of the lock will be necessary step.
There is a possible TOCTOU issue when checking for the pool length, and
queueing the new allocated skb, but, this is not an issue, given that
an extra SKB in the pool is harmless and it will be eventually used. |
| In the Linux kernel, the following vulnerability has been resolved:
hfsplus: fix missing hfs_bnode_get() in __hfs_bnode_create
When sync() and link() are called concurrently, both threads may
enter hfs_bnode_find() without finding the node in the hash table
and proceed to create it.
Thread A:
hfsplus_write_inode()
-> hfsplus_write_system_inode()
-> hfs_btree_write()
-> hfs_bnode_find(tree, 0)
-> __hfs_bnode_create(tree, 0)
Thread B:
hfsplus_create_cat()
-> hfs_brec_insert()
-> hfs_bnode_split()
-> hfs_bmap_alloc()
-> hfs_bnode_find(tree, 0)
-> __hfs_bnode_create(tree, 0)
In this case, thread A creates the bnode, sets refcnt=1, and hashes it.
Thread B also tries to create the same bnode, notices it has already
been inserted, drops its own instance, and uses the hashed one without
getting the node.
```
node2 = hfs_bnode_findhash(tree, cnid);
if (!node2) { <- Thread A
hash = hfs_bnode_hash(cnid);
node->next_hash = tree->node_hash[hash];
tree->node_hash[hash] = node;
tree->node_hash_cnt++;
} else { <- Thread B
spin_unlock(&tree->hash_lock);
kfree(node);
wait_event(node2->lock_wq,
!test_bit(HFS_BNODE_NEW, &node2->flags));
return node2;
}
```
However, hfs_bnode_find() requires each call to take a reference.
Here both threads end up setting refcnt=1. When they later put the node,
this triggers:
BUG_ON(!atomic_read(&node->refcnt))
In this scenario, Thread B in fact finds the node in the hash table
rather than creating a new one, and thus must take a reference.
Fix this by calling hfs_bnode_get() when reusing a bnode newly created by
another thread to ensure the refcount is updated correctly.
A similar bug was fixed in HFS long ago in commit
a9dc087fd3c4 ("fix missing hfs_bnode_get() in __hfs_bnode_create")
but the same issue remained in HFS+ until now. |
