CVE-2024-26612: netfs, fscache: Prevent Oops in fscache_put_cache()

CVE-2024-26612: netfs, fscache: Prevent Oops in fscache_put_cache()

[Lee Jones]

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

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

netfs, fscache: Prevent Oops in fscache_put_cache()

This function dereferences "cache" and then checks if it's
IS_ERR_OR_NULL().  Check first, then dereference.

The Linux kernel CVE team has assigned CVE-2024-26612 to this issue.


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

	Issue introduced in 5.17 with commit 9549332df4ed and fixed in 6.1.76 with commit 82a9bc343ba0
	Issue introduced in 5.17 with commit 9549332df4ed and fixed in 6.6.15 with commit 1c45256e5990
	Issue introduced in 5.17 with commit 9549332df4ed and fixed in 6.7.3 with commit 4200ad3e46ce
	Issue introduced in 5.17 with commit 9549332df4ed and fixed in 6.8-rc2 with commit 3be0b3ed1d76

Please see https://www.kernel.org or 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-2024-26612
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/netfs/fscache_cache.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/82a9bc343ba019665d3ddc1d9a180bf0e0390cf3
	https://git.kernel.org/stable/c/1c45256e599061021e2c848952e50f406457e448
	https://git.kernel.org/stable/c/4200ad3e46ce50f410fdda302745489441bc70f0
	https://git.kernel.org/stable/c/3be0b3ed1d76c6703b9ee482b55f7e01c369cc68