Subject: CVE-2024-35874: aio: Fix null ptr deref in aio_complete() wakeup

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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

aio: Fix null ptr deref in aio_complete() wakeup

list_del_init_careful() needs to be the last access to the wait queue
entry - it effectively unlocks access.

Previously, finish_wait() would see the empty list head and skip taking
the lock, and then we'd return - but the completion path would still
attempt to do the wakeup after the task_struct pointer had been
overwritten.

The Linux kernel CVE team has assigned CVE-2024-35874 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 6.8 with commit 71eb6b6b0ba9 and fixed in 6.8.5 with commit 9678bcc6234d
	Issue introduced in 6.8 with commit 71eb6b6b0ba9 and fixed in 6.9 with commit caeb4b0a11b3

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2024-35874
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	fs/aio.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/9678bcc6234d83759fe091c197f5017a32b468da
	https://git.kernel.org/stable/c/caeb4b0a11b3393e43f7fa8e0a5a18462acc66bd