Vulnerability CVE-2024-27023
Published: 2024-05-01

Description:
In the Linux kernel, the following vulnerability has been resolved:

md: Fix missing release of 'active_io' for flush

submit_flushes
atomic_set(&mddev->flush_pending, 1);
rdev_for_each_rcu(rdev, mddev)
atomic_inc(&mddev->flush_pending);
bi->bi_end_io = md_end_flush
submit_bio(bi);
/* flush io is done first */
md_end_flush
if (atomic_dec_and_test(&mddev->flush_pending))
percpu_ref_put(&mddev->active_io)
-> active_io is not released

if (atomic_dec_and_test(&mddev->flush_pending))
-> missing release of active_io

For consequence, mddev_suspend() will wait for 'active_io' to be zero
forever.

Fix this problem by releasing 'active_io' in submit_flushes() if
'flush_pending' is decreased to zero.

 References:
https://git.kernel.org/stable/c/6b2ff10390b19a2364af622b6666b690443f9f3f
https://git.kernel.org/stable/c/02dad157ba11064d073f5499dc33552b227d5d3a
https://git.kernel.org/stable/c/11f81438927f84edfaaeb5d5f10856c3a1c1fc82
https://git.kernel.org/stable/c/855678ed8534518e2b428bcbcec695de9ba248e8
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