linux-cve-announce - CVE-2025-40320: smb: client: fix potential cfid UAF in smb2_query_info

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Message-ID: <2025120823-CVE-2025-40320-8b44@gregkh>
Date: Mon,  8 Dec 2025 09:47:44 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-40320: smb: client: fix potential cfid UAF in smb2_query_info_compound

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

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

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

smb: client: fix potential cfid UAF in smb2_query_info_compound

When smb2_query_info_compound() retries, a previously allocated cfid may
have been freed in the first attempt.
Because cfid wasn't reset on replay, later cleanup could act on a stale
pointer, leading to a potential use-after-free.

Reinitialize cfid to NULL under the replay label.

Example trace (trimmed):

refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 11224 at ../lib/refcount.c:28 refcount_warn_saturate+0x9c/0x110
[...]
RIP: 0010:refcount_warn_saturate+0x9c/0x110
[...]
Call Trace:
 <TASK>
 smb2_query_info_compound+0x29c/0x5c0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]
 ? step_into+0x10d/0x690
 ? __legitimize_path+0x28/0x60
 smb2_queryfs+0x6a/0xf0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]
 smb311_queryfs+0x12d/0x140 [cifs f90b72658819bd21c94769b6a652029a07a7172f]
 ? kmem_cache_alloc+0x18a/0x340
 ? getname_flags+0x46/0x1e0
 cifs_statfs+0x9f/0x2b0 [cifs f90b72658819bd21c94769b6a652029a07a7172f]
 statfs_by_dentry+0x67/0x90
 vfs_statfs+0x16/0xd0
 user_statfs+0x54/0xa0
 __do_sys_statfs+0x20/0x50
 do_syscall_64+0x58/0x80

The Linux kernel CVE team has assigned CVE-2025-40320 to this issue.


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

	Issue introduced in 6.6.32 with commit 433042a91f9373241307725b52de573933ffedbf and fixed in 6.6.117 with commit 939c4e33005e2a56ea8fcedddf0da92df864bd3b
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 6.12.58 with commit 327f89c21601ebb7889f8c97754b76f08ce95a0c
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 6.17.8 with commit b556c278d43f4707a9073ca74d55581b4f279806
	Issue introduced in 6.8 with commit 4f1fffa2376922f3d1d506e49c0fd445b023a28e and fixed in 6.18 with commit 5c76f9961c170552c1d07c830b5e145475151600

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-2025-40320
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/smb/client/smb2ops.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/939c4e33005e2a56ea8fcedddf0da92df864bd3b
	https://git.kernel.org/stable/c/327f89c21601ebb7889f8c97754b76f08ce95a0c
	https://git.kernel.org/stable/c/b556c278d43f4707a9073ca74d55581b4f279806
	https://git.kernel.org/stable/c/5c76f9961c170552c1d07c830b5e145475151600