Message-ID: <2025050115-CVE-2022-49769-d028@gregkh>
Date: Thu,  1 May 2025 16:09:19 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-49769: gfs2: Check sb_bsize_shift after reading superblock

From: Greg Kroah-Hartman <gregkh@...nel.org>

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

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

gfs2: Check sb_bsize_shift after reading superblock

Fuzzers like to scribble over sb_bsize_shift but in reality it's very
unlikely that this field would be corrupted on its own. Nevertheless it
should be checked to avoid the possibility of messy mount errors due to
bad calculations. It's always a fixed value based on the block size so
we can just check that it's the expected value.

Tested with:

    mkfs.gfs2 -O -p lock_nolock /dev/vdb
    for i in 0 -1 64 65 32 33; do
        gfs2_edit -p sb field sb_bsize_shift $i /dev/vdb
        mount /dev/vdb /mnt/test && umount /mnt/test
    done

Before this patch we get a withdraw after

[   76.413681] gfs2: fsid=loop0.0: fatal: invalid metadata block
[   76.413681]   bh = 19 (type: exp=5, found=4)
[   76.413681]   function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 492

and with UBSAN configured we also get complaints like

[   76.373395] UBSAN: shift-out-of-bounds in fs/gfs2/ops_fstype.c:295:19
[   76.373815] shift exponent 4294967287 is too large for 64-bit type 'long unsigned int'

After the patch, these complaints don't appear, mount fails immediately
and we get an explanation in dmesg.

The Linux kernel CVE team has assigned CVE-2022-49769 to this issue.


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

	Fixed in 4.9.334 with commit d6b1e8ea6f3418c3b461ad5a35cdc93c996b2c87
	Fixed in 4.14.300 with commit 1ad197097343568066a8ffaa27ee7d0ae6d9f476
	Fixed in 4.19.267 with commit 15c83fa0fd659dd9fbdc940a560b61236e876a80
	Fixed in 5.4.225 with commit 8b6534c9ae9dba5489703a19d8ba6c8f2cfa33c2
	Fixed in 5.10.156 with commit 5fa30be7ba81191b0a0c7239a89befc0c94286d5
	Fixed in 5.15.80 with commit 28275a7c84d21c55ab3282d897f284d8d527173c
	Fixed in 6.0.10 with commit 16670534c7cff1acd918a6a5ec751b14e7436b76
	Fixed in 6.1 with commit 670f8ce56dd0632dc29a0322e188cc73ce3c6b92

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-2022-49769
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/gfs2/ops_fstype.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/d6b1e8ea6f3418c3b461ad5a35cdc93c996b2c87
	https://git.kernel.org/stable/c/1ad197097343568066a8ffaa27ee7d0ae6d9f476
	https://git.kernel.org/stable/c/15c83fa0fd659dd9fbdc940a560b61236e876a80
	https://git.kernel.org/stable/c/8b6534c9ae9dba5489703a19d8ba6c8f2cfa33c2
	https://git.kernel.org/stable/c/5fa30be7ba81191b0a0c7239a89befc0c94286d5
	https://git.kernel.org/stable/c/28275a7c84d21c55ab3282d897f284d8d527173c
	https://git.kernel.org/stable/c/16670534c7cff1acd918a6a5ec751b14e7436b76
	https://git.kernel.org/stable/c/670f8ce56dd0632dc29a0322e188cc73ce3c6b92

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