linux-cve-announce - CVE-2024-53130: nilfs2: fix null-ptr-deref in block_dirty

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Message-ID: <2024120450-CVE-2024-53130-5621@gregkh>
Date: Wed,  4 Dec 2024 15:20:53 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-53130: nilfs2: fix null-ptr-deref in block_dirty_buffer tracepoint

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

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

nilfs2: fix null-ptr-deref in block_dirty_buffer tracepoint

When using the "block:block_dirty_buffer" tracepoint, mark_buffer_dirty()
may cause a NULL pointer dereference, or a general protection fault when
KASAN is enabled.

This happens because, since the tracepoint was added in
mark_buffer_dirty(), it references the dev_t member bh->b_bdev->bd_dev
regardless of whether the buffer head has a pointer to a block_device
structure.

In the current implementation, nilfs_grab_buffer(), which grabs a buffer
to read (or create) a block of metadata, including b-tree node blocks,
does not set the block device, but instead does so only if the buffer is
not in the "uptodate" state for each of its caller block reading
functions.  However, if the uptodate flag is set on a folio/page, and the
buffer heads are detached from it by try_to_free_buffers(), and new buffer
heads are then attached by create_empty_buffers(), the uptodate flag may
be restored to each buffer without the block device being set to
bh->b_bdev, and mark_buffer_dirty() may be called later in that state,
resulting in the bug mentioned above.

Fix this issue by making nilfs_grab_buffer() always set the block device
of the super block structure to the buffer head, regardless of the state
of the buffer's uptodate flag.

The Linux kernel CVE team has assigned CVE-2024-53130 to this issue.

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

	Issue introduced in 3.9 with commit 5305cb830834 and fixed in 6.1.119 with commit 86b19031dbc7
	Issue introduced in 3.9 with commit 5305cb830834 and fixed in 6.6.63 with commit b0e476574004
	Issue introduced in 3.9 with commit 5305cb830834 and fixed in 6.11.10 with commit ffc440a76a0f
	Issue introduced in 3.9 with commit 5305cb830834 and fixed in 6.12 with commit 2026559a6c4c

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-2024-53130
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/nilfs2/btnode.c
	fs/nilfs2/gcinode.c
	fs/nilfs2/mdt.c
	fs/nilfs2/page.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/86b19031dbc79abc378dfae357f6ea33ebeb0c95
	https://git.kernel.org/stable/c/b0e4765740040c44039282057ecacd7435d1d2ba
	https://git.kernel.org/stable/c/ffc440a76a0f476a7e6ea838ec0dc8e9979944d1
	https://git.kernel.org/stable/c/2026559a6c4ce34db117d2db8f710fe2a9420d5a