Subject: CVE-2024-46688: erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially fails

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

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

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

erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially fails

If z_erofs_gbuf_growsize() partially fails on a global buffer due to
memory allocation failure or fault injection (as reported by syzbot [1]),
new pages need to be freed by comparing to the existing pages to avoid
memory leaks.

However, the old gbuf->pages[] array may not be large enough, which can
lead to null-ptr-deref or out-of-bound access.

Fix this by checking against gbuf->nrpages in advance.

[1] https://lore.kernel.org/r/[email-masked]

The Linux kernel CVE team has assigned CVE-2024-46688 to this issue.

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

	Issue introduced in 6.10 with commit d6db47e571dc and fixed in 6.10.8 with commit 49c0e0819980
	Issue introduced in 6.10 with commit d6db47e571dc and fixed in 6.11 with commit 0005e01e1e87

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-2024-46688
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/erofs/zutil.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/49c0e081998008cde0c872c0ff9affa1ece4b878
	https://git.kernel.org/stable/c/0005e01e1e875c5e27130c5e2ed0189749d1e08a