linux-cve-announce - CVE-2025-37742: jfs: Fix uninit-value access of imap allocated in the diMount() function

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Message-ID: <2025050134-CVE-2025-37742-60be@gregkh>
Date: Thu,  1 May 2025 14:56:48 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37742: jfs: Fix uninit-value access of imap allocated in the diMount() function

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

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

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

jfs: Fix uninit-value access of imap allocated in the diMount() function

syzbot reports that hex_dump_to_buffer is using uninit-value:

=====================================================
BUG: KMSAN: uninit-value in hex_dump_to_buffer+0x888/0x1100 lib/hexdump.c:171
hex_dump_to_buffer+0x888/0x1100 lib/hexdump.c:171
print_hex_dump+0x13d/0x3e0 lib/hexdump.c:276
diFree+0x5ba/0x4350 fs/jfs/jfs_imap.c:876
jfs_evict_inode+0x510/0x550 fs/jfs/inode.c:156
evict+0x723/0xd10 fs/inode.c:796
iput_final fs/inode.c:1946 [inline]
iput+0x97b/0xdb0 fs/inode.c:1972
txUpdateMap+0xf3e/0x1150 fs/jfs/jfs_txnmgr.c:2367
txLazyCommit fs/jfs/jfs_txnmgr.c:2664 [inline]
jfs_lazycommit+0x627/0x11d0 fs/jfs/jfs_txnmgr.c:2733
kthread+0x6b9/0xef0 kernel/kthread.c:464
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4121 [inline]
slab_alloc_node mm/slub.c:4164 [inline]
__kmalloc_cache_noprof+0x8e3/0xdf0 mm/slub.c:4320
kmalloc_noprof include/linux/slab.h:901 [inline]
diMount+0x61/0x7f0 fs/jfs/jfs_imap.c:105
jfs_mount+0xa8e/0x11d0 fs/jfs/jfs_mount.c:176
jfs_fill_super+0xa47/0x17c0 fs/jfs/super.c:523
get_tree_bdev_flags+0x6ec/0x910 fs/super.c:1636
get_tree_bdev+0x37/0x50 fs/super.c:1659
jfs_get_tree+0x34/0x40 fs/jfs/super.c:635
vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
do_new_mount+0x71f/0x15e0 fs/namespace.c:3560
path_mount+0x742/0x1f10 fs/namespace.c:3887
do_mount fs/namespace.c:3900 [inline]
__do_sys_mount fs/namespace.c:4111 [inline]
__se_sys_mount+0x71f/0x800 fs/namespace.c:4088
__x64_sys_mount+0xe4/0x150 fs/namespace.c:4088
x64_sys_call+0x39bf/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
=====================================================

The reason is that imap is not properly initialized after memory
allocation. It will cause the snprintf() function to write uninitialized
data into linebuf within hex_dump_to_buffer().

Fix this by using kzalloc instead of kmalloc to clear its content at the
beginning in diMount().

The Linux kernel CVE team has assigned CVE-2025-37742 to this issue.


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

	Fixed in 6.1.135 with commit cab1852368dd74d629ee02abdbc559218ca64dde
	Fixed in 6.6.88 with commit 067347e00a3a7d04afed93f080c6c131e5dd15ee
	Fixed in 6.12.24 with commit 63148ce4904faa668daffdd1d3c1199ae315ef2c
	Fixed in 6.13.12 with commit 7057f3aab47629d38e54eae83505813cf0da1e4b
	Fixed in 6.14.3 with commit d0d7eca253ccd0619b3d2b683ffe32218ebca9ac
	Fixed in 6.15-rc1 with commit 9629d7d66c621671d9a47afe27ca9336bfc8a9ea

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-2025-37742
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/jfs/jfs_imap.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/cab1852368dd74d629ee02abdbc559218ca64dde
	https://git.kernel.org/stable/c/067347e00a3a7d04afed93f080c6c131e5dd15ee
	https://git.kernel.org/stable/c/63148ce4904faa668daffdd1d3c1199ae315ef2c
	https://git.kernel.org/stable/c/7057f3aab47629d38e54eae83505813cf0da1e4b
	https://git.kernel.org/stable/c/d0d7eca253ccd0619b3d2b683ffe32218ebca9ac
	https://git.kernel.org/stable/c/9629d7d66c621671d9a47afe27ca9336bfc8a9ea