linux-cve-announce - CVE-2024-26982: Squashfs: check the inode number is not the invalid value of zero

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Message-ID: <2024050141-CVE-2024-26982-8675@gregkh>
Date: Wed,  1 May 2024 07:30:43 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-26982: Squashfs: check the inode number is not the invalid value of zero

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

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

Squashfs: check the inode number is not the invalid value of zero

Syskiller has produced an out of bounds access in fill_meta_index().

That out of bounds access is ultimately caused because the inode
has an inode number with the invalid value of zero, which was not checked.

The reason this causes the out of bounds access is due to following
sequence of events:

1. Fill_meta_index() is called to allocate (via empty_meta_index())
   and fill a metadata index.  It however suffers a data read error
   and aborts, invalidating the newly returned empty metadata index.
   It does this by setting the inode number of the index to zero,
   which means unused (zero is not a valid inode number).

2. When fill_meta_index() is subsequently called again on another
   read operation, locate_meta_index() returns the previous index
   because it matches the inode number of 0.  Because this index
   has been returned it is expected to have been filled, and because
   it hasn't been, an out of bounds access is performed.

This patch adds a sanity check which checks that the inode number
is not zero when the inode is created and returns -EINVAL if it is.

[phillip@...ashfs.org.uk: whitespace fix]
  Link: https://lkml.kernel.org/r/20240409204723.446925-1-phillip@squashfs.org.uk

The Linux kernel CVE team has assigned CVE-2024-26982 to this issue.

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

	Fixed in 6.8.8 with commit 7def00ebc9f2
	Fixed in 6.9-rc5 with commit 9253c54e01b6

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-2024-26982
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/squashfs/inode.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/7def00ebc9f2d6a581ddf46ce4541f84a10680e5
	https://git.kernel.org/stable/c/9253c54e01b6505d348afbc02abaa4d9f8a01395