Improper Input Validation The advisory has been revoked - it doesn't affect any version of package kernel-64k-modules-extra (opens in a new tab)
Threat Intelligence
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Start learning- Snyk IDSNYK-CENTOS9-KERNEL64KMODULESEXTRA-6288583
- published28 Feb 2024
- disclosed27 Feb 2024
Introduced: 27 Feb 2024
CVE-2021-46942 (opens in a new tab)Amendment
The Centos security team deemed this advisory irrelevant for Centos:9.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-64k-modules-extra package and not the kernel-64k-modules-extra package as distributed by Centos.
In the Linux kernel, the following vulnerability has been resolved:
io_uring: fix shared sqpoll cancellation hangs
[ 736.982891] INFO: task iou-sqp-4294:4295 blocked for more than 122 seconds. [ 736.982897] Call Trace: [ 736.982901] schedule+0x68/0xe0 [ 736.982903] io_uring_cancel_sqpoll+0xdb/0x110 [ 736.982908] io_sqpoll_cancel_cb+0x24/0x30 [ 736.982911] io_run_task_work_head+0x28/0x50 [ 736.982913] io_sq_thread+0x4e3/0x720
We call io_uring_cancel_sqpoll() one by one for each ctx either in sq_thread() itself or via task works, and it's intended to cancel all requests of a specified context. However the function uses per-task counters to track the number of inflight requests, so it counts more requests than available via currect io_uring ctx and goes to sleep for them to appear (e.g. from IRQ), that will never happen.
Cancel a bit more than before, i.e. all ctxs that share sqpoll and continue to use shared counters. Don't forget that we should not remove ctx from the list before running that task_work sqpoll-cancel, otherwise the function wouldn't be able to find the context and will hang.