| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
nilfs2: fix deadlock in nilfs_count_free_blocks()
A semaphore deadlock can occur if nilfs_get_block() detects metadata
corruption while locating data blocks and a superblock writeback occurs at
the same time:
task 1 task 2
------ ------
* A file operation *
nilfs_truncate()
nilfs_get_block()
down_read(rwsem A) <--
nilfs_bmap_lookup_contig()
... generic_shutdown_super()
nilfs_put_super()
* Prepare to write superblock *
down_write(rwsem B) <--
nilfs_cleanup_super()
* Detect b-tree corruption * nilfs_set_log_cursor()
nilfs_bmap_convert_error() nilfs_count_free_blocks()
__nilfs_error() down_read(rwsem A) <--
nilfs_set_error()
down_write(rwsem B) <--
*** DEADLOCK ***
Here, nilfs_get_block() readlocks rwsem A (= NILFS_MDT(dat_inode)->mi_sem)
and then calls nilfs_bmap_lookup_contig(), but if it fails due to metadata
corruption, __nilfs_error() is called from nilfs_bmap_convert_error()
inside the lock section.
Since __nilfs_error() calls nilfs_set_error() unless the filesystem is
read-only and nilfs_set_error() attempts to writelock rwsem B (=
nilfs->ns_sem) to write back superblock exclusively, hierarchical lock
acquisition occurs in the order rwsem A -> rwsem B.
Now, if another task starts updating the superblock, it may writelock
rwsem B during the lock sequence above, and can deadlock trying to
readlock rwsem A in nilfs_count_free_blocks().
However, there is actually no need to take rwsem A in
nilfs_count_free_blocks() because it, within the lock section, only reads
a single integer data on a shared struct with
nilfs_sufile_get_ncleansegs(). This has been the case after commit
aa474a220180 ("nilfs2: add local variable to cache the number of clean
segments"), that is, even before this bug was introduced.
So, this resolves the deadlock problem by just not taking the semaphore in
nilfs_count_free_blocks(). |
| In the Linux kernel, the following vulnerability has been resolved:
net: ks8851: Queue RX packets in IRQ handler instead of disabling BHs
Currently the driver uses local_bh_disable()/local_bh_enable() in its
IRQ handler to avoid triggering net_rx_action() softirq on exit from
netif_rx(). The net_rx_action() could trigger this driver .start_xmit
callback, which is protected by the same lock as the IRQ handler, so
calling the .start_xmit from netif_rx() from the IRQ handler critical
section protected by the lock could lead to an attempt to claim the
already claimed lock, and a hang.
The local_bh_disable()/local_bh_enable() approach works only in case
the IRQ handler is protected by a spinlock, but does not work if the
IRQ handler is protected by mutex, i.e. this works for KS8851 with
Parallel bus interface, but not for KS8851 with SPI bus interface.
Remove the BH manipulation and instead of calling netif_rx() inside
the IRQ handler code protected by the lock, queue all the received
SKBs in the IRQ handler into a queue first, and once the IRQ handler
exits the critical section protected by the lock, dequeue all the
queued SKBs and push them all into netif_rx(). At this point, it is
safe to trigger the net_rx_action() softirq, since the netif_rx()
call is outside of the lock that protects the IRQ handler. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: make cow_file_range_inline() honor locked_page on error
The btrfs buffered write path runs through __extent_writepage() which
has some tricky return value handling for writepage_delalloc().
Specifically, when that returns 1, we exit, but for other return values
we continue and end up calling btrfs_folio_end_all_writers(). If the
folio has been unlocked (note that we check the PageLocked bit at the
start of __extent_writepage()), this results in an assert panic like
this one from syzbot:
BTRFS: error (device loop0 state EAL) in free_log_tree:3267: errno=-5 IO failure
BTRFS warning (device loop0 state EAL): Skipping commit of aborted transaction.
BTRFS: error (device loop0 state EAL) in cleanup_transaction:2018: errno=-5 IO failure
assertion failed: folio_test_locked(folio), in fs/btrfs/subpage.c:871
------------[ cut here ]------------
kernel BUG at fs/btrfs/subpage.c:871!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 PID: 5090 Comm: syz-executor225 Not tainted
6.10.0-syzkaller-05505-gb1bc554e009e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 06/27/2024
RIP: 0010:btrfs_folio_end_all_writers+0x55b/0x610 fs/btrfs/subpage.c:871
Code: e9 d3 fb ff ff e8 25 22 c2 fd 48 c7 c7 c0 3c 0e 8c 48 c7 c6 80 3d
0e 8c 48 c7 c2 60 3c 0e 8c b9 67 03 00 00 e8 66 47 ad 07 90 <0f> 0b e8
6e 45 b0 07 4c 89 ff be 08 00 00 00 e8 21 12 25 fe 4c 89
RSP: 0018:ffffc900033d72e0 EFLAGS: 00010246
RAX: 0000000000000045 RBX: 00fff0000000402c RCX: 663b7a08c50a0a00
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc900033d73b0 R08: ffffffff8176b98c R09: 1ffff9200067adfc
R10: dffffc0000000000 R11: fffff5200067adfd R12: 0000000000000001
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffea0001cbee80
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f076012f8 CR3: 000000000e134000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__extent_writepage fs/btrfs/extent_io.c:1597 [inline]
extent_write_cache_pages fs/btrfs/extent_io.c:2251 [inline]
btrfs_writepages+0x14d7/0x2760 fs/btrfs/extent_io.c:2373
do_writepages+0x359/0x870 mm/page-writeback.c:2656
filemap_fdatawrite_wbc+0x125/0x180 mm/filemap.c:397
__filemap_fdatawrite_range mm/filemap.c:430 [inline]
__filemap_fdatawrite mm/filemap.c:436 [inline]
filemap_flush+0xdf/0x130 mm/filemap.c:463
btrfs_release_file+0x117/0x130 fs/btrfs/file.c:1547
__fput+0x24a/0x8a0 fs/file_table.c:422
task_work_run+0x24f/0x310 kernel/task_work.c:222
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0xa2f/0x27f0 kernel/exit.c:877
do_group_exit+0x207/0x2c0 kernel/exit.c:1026
__do_sys_exit_group kernel/exit.c:1037 [inline]
__se_sys_exit_group kernel/exit.c:1035 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1035
x64_sys_call+0x2634/0x2640
arch/x86/include/generated/asm/syscalls_64.h:232
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5f075b70c9
Code: Unable to access opcode bytes at
0x7f5f075b709f.
I was hitting the same issue by doing hundreds of accelerated runs of
generic/475, which also hits IO errors by design.
I instrumented that reproducer with bpftrace and found that the
undesirable folio_unlock was coming from the following callstack:
folio_unlock+5
__process_pages_contig+475
cow_file_range_inline.constprop.0+230
cow_file_range+803
btrfs_run_delalloc_range+566
writepage_delalloc+332
__extent_writepage # inlined in my stacktrace, but I added it here
extent_write_cache_pages+622
Looking at the bisected-to pa
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: Add a lock when accessing the buddy trim function
When running YouTube videos and Steam games simultaneously,
the tester found a system hang / race condition issue with
the multi-display configuration setting. Adding a lock to
the buddy allocator's trim function would be the solution.
<log snip>
[ 7197.250436] general protection fault, probably for non-canonical address 0xdead000000000108
[ 7197.250447] RIP: 0010:__alloc_range+0x8b/0x340 [amddrm_buddy]
[ 7197.250470] Call Trace:
[ 7197.250472] <TASK>
[ 7197.250475] ? show_regs+0x6d/0x80
[ 7197.250481] ? die_addr+0x37/0xa0
[ 7197.250483] ? exc_general_protection+0x1db/0x480
[ 7197.250488] ? drm_suballoc_new+0x13c/0x93d [drm_suballoc_helper]
[ 7197.250493] ? asm_exc_general_protection+0x27/0x30
[ 7197.250498] ? __alloc_range+0x8b/0x340 [amddrm_buddy]
[ 7197.250501] ? __alloc_range+0x109/0x340 [amddrm_buddy]
[ 7197.250506] amddrm_buddy_block_trim+0x1b5/0x260 [amddrm_buddy]
[ 7197.250511] amdgpu_vram_mgr_new+0x4f5/0x590 [amdgpu]
[ 7197.250682] amdttm_resource_alloc+0x46/0xb0 [amdttm]
[ 7197.250689] ttm_bo_alloc_resource+0xe4/0x370 [amdttm]
[ 7197.250696] amdttm_bo_validate+0x9d/0x180 [amdttm]
[ 7197.250701] amdgpu_bo_pin+0x15a/0x2f0 [amdgpu]
[ 7197.250831] amdgpu_dm_plane_helper_prepare_fb+0xb2/0x360 [amdgpu]
[ 7197.251025] ? try_wait_for_completion+0x59/0x70
[ 7197.251030] drm_atomic_helper_prepare_planes.part.0+0x2f/0x1e0
[ 7197.251035] drm_atomic_helper_prepare_planes+0x5d/0x70
[ 7197.251037] drm_atomic_helper_commit+0x84/0x160
[ 7197.251040] drm_atomic_nonblocking_commit+0x59/0x70
[ 7197.251043] drm_mode_atomic_ioctl+0x720/0x850
[ 7197.251047] ? __pfx_drm_mode_atomic_ioctl+0x10/0x10
[ 7197.251049] drm_ioctl_kernel+0xb9/0x120
[ 7197.251053] ? srso_alias_return_thunk+0x5/0xfbef5
[ 7197.251056] drm_ioctl+0x2d4/0x550
[ 7197.251058] ? __pfx_drm_mode_atomic_ioctl+0x10/0x10
[ 7197.251063] amdgpu_drm_ioctl+0x4e/0x90 [amdgpu]
[ 7197.251186] __x64_sys_ioctl+0xa0/0xf0
[ 7197.251190] x64_sys_call+0x143b/0x25c0
[ 7197.251193] do_syscall_64+0x7f/0x180
[ 7197.251197] ? srso_alias_return_thunk+0x5/0xfbef5
[ 7197.251199] ? amdgpu_display_user_framebuffer_create+0x215/0x320 [amdgpu]
[ 7197.251329] ? drm_internal_framebuffer_create+0xb7/0x1a0
[ 7197.251332] ? srso_alias_return_thunk+0x5/0xfbef5
(cherry picked from commit 3318ba94e56b9183d0304577c74b33b6b01ce516) |
| In the Linux kernel, the following vulnerability has been resolved:
nvme: fix reconnection fail due to reserved tag allocation
We found a issue on production environment while using NVMe over RDMA,
admin_q reconnect failed forever while remote target and network is ok.
After dig into it, we found it may caused by a ABBA deadlock due to tag
allocation. In my case, the tag was hold by a keep alive request
waiting inside admin_q, as we quiesced admin_q while reset ctrl, so the
request maked as idle and will not process before reset success. As
fabric_q shares tagset with admin_q, while reconnect remote target, we
need a tag for connect command, but the only one reserved tag was held
by keep alive command which waiting inside admin_q. As a result, we
failed to reconnect admin_q forever. In order to fix this issue, I
think we should keep two reserved tags for admin queue. |
| In the Linux kernel, the following vulnerability has been resolved:
lib: alloc_tag_module_unload must wait for pending kfree_rcu calls
Ben Greear reports following splat:
------------[ cut here ]------------
net/netfilter/nf_nat_core.c:1114 module nf_nat func:nf_nat_register_fn has 256 allocated at module unload
WARNING: CPU: 1 PID: 10421 at lib/alloc_tag.c:168 alloc_tag_module_unload+0x22b/0x3f0
Modules linked in: nf_nat(-) btrfs ufs qnx4 hfsplus hfs minix vfat msdos fat
...
Hardware name: Default string Default string/SKYBAY, BIOS 5.12 08/04/2020
RIP: 0010:alloc_tag_module_unload+0x22b/0x3f0
codetag_unload_module+0x19b/0x2a0
? codetag_load_module+0x80/0x80
nf_nat module exit calls kfree_rcu on those addresses, but the free
operation is likely still pending by the time alloc_tag checks for leaks.
Wait for outstanding kfree_rcu operations to complete before checking
resolves this warning.
Reproducer:
unshare -n iptables-nft -t nat -A PREROUTING -p tcp
grep nf_nat /proc/allocinfo # will list 4 allocations
rmmod nft_chain_nat
rmmod nf_nat # will WARN.
[akpm@linux-foundation.org: add comment] |
| In the Linux kernel, the following vulnerability has been resolved:
debugfs: fix wait/cancellation handling during remove
Ben Greear further reports deadlocks during concurrent debugfs
remove while files are being accessed, even though the code in
question now uses debugfs cancellations. Turns out that despite
all the review on the locking, we missed completely that the
logic is wrong: if the refcount hits zero we can finish (and
need not wait for the completion), but if it doesn't we have
to trigger all the cancellations. As written, we can _never_
get into the loop triggering the cancellations. Fix this, and
explain it better while at it. |
| In the Linux kernel, the following vulnerability has been resolved:
LoongArch: Define the __io_aw() hook as mmiowb()
Commit fb24ea52f78e0d595852e ("drivers: Remove explicit invocations of
mmiowb()") remove all mmiowb() in drivers, but it says:
"NOTE: mmiowb() has only ever guaranteed ordering in conjunction with
spin_unlock(). However, pairing each mmiowb() removal in this patch with
the corresponding call to spin_unlock() is not at all trivial, so there
is a small chance that this change may regress any drivers incorrectly
relying on mmiowb() to order MMIO writes between CPUs using lock-free
synchronisation."
The mmio in radeon_ring_commit() is protected by a mutex rather than a
spinlock, but in the mutex fastpath it behaves similar to spinlock. We
can add mmiowb() calls in the radeon driver but the maintainer says he
doesn't like such a workaround, and radeon is not the only example of
mutex protected mmio.
So we should extend the mmiowb tracking system from spinlock to mutex,
and maybe other locking primitives. This is not easy and error prone, so
we solve it in the architectural code, by simply defining the __io_aw()
hook as mmiowb(). And we no longer need to override queued_spin_unlock()
so use the generic definition.
Without this, we get such an error when run 'glxgears' on weak ordering
architectures such as LoongArch:
radeon 0000:04:00.0: ring 0 stalled for more than 10324msec
radeon 0000:04:00.0: ring 3 stalled for more than 10240msec
radeon 0000:04:00.0: GPU lockup (current fence id 0x000000000001f412 last fence id 0x000000000001f414 on ring 3)
radeon 0000:04:00.0: GPU lockup (current fence id 0x000000000000f940 last fence id 0x000000000000f941 on ring 0)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35)
radeon 0000:04:00.0: scheduling IB failed (-35).
[drm:radeon_gem_va_ioctl [radeon]] *ERROR* Couldn't update BO_VA (-35) |
| In the Linux kernel, the following vulnerability has been resolved:
ext4: fix racy may inline data check in dio write
syzbot reports that the following warning from ext4_iomap_begin()
triggers as of the commit referenced below:
if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
return -ERANGE;
This occurs during a dio write, which is never expected to encounter
an inode with inline data. To enforce this behavior,
ext4_dio_write_iter() checks the current inline state of the inode
and clears the MAY_INLINE_DATA state flag to either fall back to
buffered writes, or enforce that any other writers in progress on
the inode are not allowed to create inline data.
The problem is that the check for existing inline data and the state
flag can span a lock cycle. For example, if the ilock is originally
locked shared and subsequently upgraded to exclusive, another writer
may have reacquired the lock and created inline data before the dio
write task acquires the lock and proceeds.
The commit referenced below loosens the lock requirements to allow
some forms of unaligned dio writes to occur under shared lock, but
AFAICT the inline data check was technically already racy for any
dio write that would have involved a lock cycle. Regardless, lift
clearing of the state bit to the same lock critical section that
checks for preexisting inline data on the inode to close the race. |
| In the Linux kernel, the following vulnerability has been resolved:
ALSA: scarlett2: Add missing mutex lock around get meter levels
As scarlett2_meter_ctl_get() uses meter_level_map[], the data_mutex
should be locked while accessing it. |
| In the Linux kernel, the following vulnerability has been resolved:
cfg80211: fix management registrations locking
The management registrations locking was broken, the list was
locked for each wdev, but cfg80211_mgmt_registrations_update()
iterated it without holding all the correct spinlocks, causing
list corruption.
Rather than trying to fix it with fine-grained locking, just
move the lock to the wiphy/rdev (still need the list on each
wdev), we already need to hold the wdev lock to change it, so
there's no contention on the lock in any case. This trivially
fixes the bug since we hold one wdev's lock already, and now
will hold the lock that protects all lists. |
| In the Linux kernel, the following vulnerability has been resolved:
net: ks8851: Handle softirqs at the end of IRQ thread to fix hang
The ks8851_irq() thread may call ks8851_rx_pkts() in case there are
any packets in the MAC FIFO, which calls netif_rx(). This netif_rx()
implementation is guarded by local_bh_disable() and local_bh_enable().
The local_bh_enable() may call do_softirq() to run softirqs in case
any are pending. One of the softirqs is net_rx_action, which ultimately
reaches the driver .start_xmit callback. If that happens, the system
hangs. The entire call chain is below:
ks8851_start_xmit_par from netdev_start_xmit
netdev_start_xmit from dev_hard_start_xmit
dev_hard_start_xmit from sch_direct_xmit
sch_direct_xmit from __dev_queue_xmit
__dev_queue_xmit from __neigh_update
__neigh_update from neigh_update
neigh_update from arp_process.constprop.0
arp_process.constprop.0 from __netif_receive_skb_one_core
__netif_receive_skb_one_core from process_backlog
process_backlog from __napi_poll.constprop.0
__napi_poll.constprop.0 from net_rx_action
net_rx_action from __do_softirq
__do_softirq from call_with_stack
call_with_stack from do_softirq
do_softirq from __local_bh_enable_ip
__local_bh_enable_ip from netif_rx
netif_rx from ks8851_irq
ks8851_irq from irq_thread_fn
irq_thread_fn from irq_thread
irq_thread from kthread
kthread from ret_from_fork
The hang happens because ks8851_irq() first locks a spinlock in
ks8851_par.c ks8851_lock_par() spin_lock_irqsave(&ksp->lock, ...)
and with that spinlock locked, calls netif_rx(). Once the execution
reaches ks8851_start_xmit_par(), it calls ks8851_lock_par() again
which attempts to claim the already locked spinlock again, and the
hang happens.
Move the do_softirq() call outside of the spinlock protected section
of ks8851_irq() by disabling BHs around the entire spinlock protected
section of ks8851_irq() handler. Place local_bh_enable() outside of
the spinlock protected section, so that it can trigger do_softirq()
without the ks8851_par.c ks8851_lock_par() spinlock being held, and
safely call ks8851_start_xmit_par() without attempting to lock the
already locked spinlock.
Since ks8851_irq() is protected by local_bh_disable()/local_bh_enable()
now, replace netif_rx() with __netif_rx() which is not duplicating the
local_bh_disable()/local_bh_enable() calls. |
| In the Linux kernel, the following vulnerability has been resolved:
dmaengine: idxd: Convert spinlock to mutex to lock evl workqueue
drain_workqueue() cannot be called safely in a spinlocked context due to
possible task rescheduling. In the multi-task scenario, calling
queue_work() while drain_workqueue() will lead to a Call Trace as
pushing a work on a draining workqueue is not permitted in spinlocked
context.
Call Trace:
<TASK>
? __warn+0x7d/0x140
? __queue_work+0x2b2/0x440
? report_bug+0x1f8/0x200
? handle_bug+0x3c/0x70
? exc_invalid_op+0x18/0x70
? asm_exc_invalid_op+0x1a/0x20
? __queue_work+0x2b2/0x440
queue_work_on+0x28/0x30
idxd_misc_thread+0x303/0x5a0 [idxd]
? __schedule+0x369/0xb40
? __pfx_irq_thread_fn+0x10/0x10
? irq_thread+0xbc/0x1b0
irq_thread_fn+0x21/0x70
irq_thread+0x102/0x1b0
? preempt_count_add+0x74/0xa0
? __pfx_irq_thread_dtor+0x10/0x10
? __pfx_irq_thread+0x10/0x10
kthread+0x103/0x140
? __pfx_kthread+0x10/0x10
ret_from_fork+0x31/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1b/0x30
</TASK>
The current implementation uses a spinlock to protect event log workqueue
and will lead to the Call Trace due to potential task rescheduling.
To address the locking issue, convert the spinlock to mutex, allowing
the drain_workqueue() to be called in a safe mutex-locked context.
This change ensures proper synchronization when accessing the event log
workqueue, preventing potential Call Trace and improving the overall
robustness of the code. |
| In the Linux kernel, the following vulnerability has been resolved:
mm/vmalloc: combine all TLB flush operations of KASAN shadow virtual address into one operation
When compiling kernel source 'make -j $(nproc)' with the up-and-running
KASAN-enabled kernel on a 256-core machine, the following soft lockup is
shown:
watchdog: BUG: soft lockup - CPU#28 stuck for 22s! [kworker/28:1:1760]
CPU: 28 PID: 1760 Comm: kworker/28:1 Kdump: loaded Not tainted 6.10.0-rc5 #95
Workqueue: events drain_vmap_area_work
RIP: 0010:smp_call_function_many_cond+0x1d8/0xbb0
Code: 38 c8 7c 08 84 c9 0f 85 49 08 00 00 8b 45 08 a8 01 74 2e 48 89 f1 49 89 f7 48 c1 e9 03 41 83 e7 07 4c 01 e9 41 83 c7 03 f3 90 <0f> b6 01 41 38 c7 7c 08 84 c0 0f 85 d4 06 00 00 8b 45 08 a8 01 75
RSP: 0018:ffffc9000cb3fb60 EFLAGS: 00000202
RAX: 0000000000000011 RBX: ffff8883bc4469c0 RCX: ffffed10776e9949
RDX: 0000000000000002 RSI: ffff8883bb74ca48 RDI: ffffffff8434dc50
RBP: ffff8883bb74ca40 R08: ffff888103585dc0 R09: ffff8884533a1800
R10: 0000000000000004 R11: ffffffffffffffff R12: ffffed1077888d39
R13: dffffc0000000000 R14: ffffed1077888d38 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8883bc400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005577b5c8d158 CR3: 0000000004850000 CR4: 0000000000350ef0
Call Trace:
<IRQ>
? watchdog_timer_fn+0x2cd/0x390
? __pfx_watchdog_timer_fn+0x10/0x10
? __hrtimer_run_queues+0x300/0x6d0
? sched_clock_cpu+0x69/0x4e0
? __pfx___hrtimer_run_queues+0x10/0x10
? srso_return_thunk+0x5/0x5f
? ktime_get_update_offsets_now+0x7f/0x2a0
? srso_return_thunk+0x5/0x5f
? srso_return_thunk+0x5/0x5f
? hrtimer_interrupt+0x2ca/0x760
? __sysvec_apic_timer_interrupt+0x8c/0x2b0
? sysvec_apic_timer_interrupt+0x6a/0x90
</IRQ>
<TASK>
? asm_sysvec_apic_timer_interrupt+0x16/0x20
? smp_call_function_many_cond+0x1d8/0xbb0
? __pfx_do_kernel_range_flush+0x10/0x10
on_each_cpu_cond_mask+0x20/0x40
flush_tlb_kernel_range+0x19b/0x250
? srso_return_thunk+0x5/0x5f
? kasan_release_vmalloc+0xa7/0xc0
purge_vmap_node+0x357/0x820
? __pfx_purge_vmap_node+0x10/0x10
__purge_vmap_area_lazy+0x5b8/0xa10
drain_vmap_area_work+0x21/0x30
process_one_work+0x661/0x10b0
worker_thread+0x844/0x10e0
? srso_return_thunk+0x5/0x5f
? __kthread_parkme+0x82/0x140
? __pfx_worker_thread+0x10/0x10
kthread+0x2a5/0x370
? __pfx_kthread+0x10/0x10
ret_from_fork+0x30/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Debugging Analysis:
1. The following ftrace log shows that the lockup CPU spends too much
time iterating vmap_nodes and flushing TLB when purging vm_area
structures. (Some info is trimmed).
kworker: funcgraph_entry: | drain_vmap_area_work() {
kworker: funcgraph_entry: | mutex_lock() {
kworker: funcgraph_entry: 1.092 us | __cond_resched();
kworker: funcgraph_exit: 3.306 us | }
... ...
kworker: funcgraph_entry: | flush_tlb_kernel_range() {
... ...
kworker: funcgraph_exit: # 7533.649 us | }
... ...
kworker: funcgraph_entry: 2.344 us | mutex_unlock();
kworker: funcgraph_exit: $ 23871554 us | }
The drain_vmap_area_work() spends over 23 seconds.
There are 2805 flush_tlb_kernel_range() calls in the ftrace log.
* One is called in __purge_vmap_area_lazy().
* Others are called by purge_vmap_node->kasan_release_vmalloc.
purge_vmap_node() iteratively releases kasan vmalloc
allocations and flushes TLB for each vmap_area.
- [Rough calculation] Each flush_tlb_kernel_range() runs
about 7.5ms.
-- 2804 * 7.5ms = 21.03 seconds.
-- That's why a soft lock is triggered.
2. Extending the soft lockup time can work around the issue (For example,
# echo
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
s390/dasd: protect device queue against concurrent access
In dasd_profile_start() the amount of requests on the device queue are
counted. The access to the device queue is unprotected against
concurrent access. With a lot of parallel I/O, especially with alias
devices enabled, the device queue can change while dasd_profile_start()
is accessing the queue. In the worst case this leads to a kernel panic
due to incorrect pointer accesses.
Fix this by taking the device lock before accessing the queue and
counting the requests. Additionally the check for a valid profile data
pointer can be done earlier to avoid unnecessary locking in a hot path. |
| In the Linux kernel, the following vulnerability has been resolved:
IB/rdmavt: add lock to call to rvt_error_qp to prevent a race condition
The documentation of the function rvt_error_qp says both r_lock and s_lock
need to be held when calling that function. It also asserts using lockdep
that both of those locks are held. However, the commit I referenced in
Fixes accidentally makes the call to rvt_error_qp in rvt_ruc_loopback no
longer covered by r_lock. This results in the lockdep assertion failing
and also possibly in a race condition. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/ast: Fix soft lockup
There is a while-loop in ast_dp_set_on_off() that could lead to
infinite-loop. This is because the register, VGACRI-Dx, checked in
this API is a scratch register actually controlled by a MCU, named
DPMCU, in BMC.
These scratch registers are protected by scu-lock. If suc-lock is not
off, DPMCU can not update these registers and then host will have soft
lockup due to never updated status.
DPMCU is used to control DP and relative registers to handshake with
host's VGA driver. Even the most time-consuming task, DP's link
training, is less than 100ms. 200ms should be enough. |
| In the Linux kernel, the following vulnerability has been resolved:
stackdepot: fix stack_depot_save_flags() in NMI context
Per documentation, stack_depot_save_flags() was meant to be usable from
NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset. However, it still
would try to take the pool_lock in an attempt to save a stack trace in the
current pool (if space is available).
This could result in deadlock if an NMI is handled while pool_lock is
already held. To avoid deadlock, only try to take the lock in NMI context
and give up if unsuccessful.
The documentation is fixed to clearly convey this. |
| In the Linux kernel, the following vulnerability has been resolved:
nfsd: Fix error cleanup path in nfsd_rename()
Commit a8b0026847b8 ("rename(): avoid a deadlock in the case of parents
having no common ancestor") added an error bail out path. However this
path does not drop the remount protection that has been acquired. Fix
the cleanup path to properly drop the remount protection. |
| In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Fix potential AB/BA lock with buffer_mutex and mmap_lock
syzbot caught a potential deadlock between the PCM
runtime->buffer_mutex and the mm->mmap_lock. It was brought by the
recent fix to cover the racy read/write and other ioctls, and in that
commit, I overlooked a (hopefully only) corner case that may take the
revert lock, namely, the OSS mmap. The OSS mmap operation
exceptionally allows to re-configure the parameters inside the OSS
mmap syscall, where mm->mmap_mutex is already held. Meanwhile, the
copy_from/to_user calls at read/write operations also take the
mm->mmap_lock internally, hence it may lead to a AB/BA deadlock.
A similar problem was already seen in the past and we fixed it with a
refcount (in commit b248371628aa). The former fix covered only the
call paths with OSS read/write and OSS ioctls, while we need to cover
the concurrent access via both ALSA and OSS APIs now.
This patch addresses the problem above by replacing the buffer_mutex
lock in the read/write operations with a refcount similar as we've
used for OSS. The new field, runtime->buffer_accessing, keeps the
number of concurrent read/write operations. Unlike the former
buffer_mutex protection, this protects only around the
copy_from/to_user() calls; the other codes are basically protected by
the PCM stream lock. The refcount can be a negative, meaning blocked
by the ioctls. If a negative value is seen, the read/write aborts
with -EBUSY. In the ioctl side, OTOH, they check this refcount, too,
and set to a negative value for blocking unless it's already being
accessed. |
