linux-cve-announce - CVE-2025-37750: smb: client: fix UAF in decryption with multichannel

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Message-ID: <2025050136-CVE-2025-37750-fdd8@gregkh>
Date: Thu,  1 May 2025 14:56:56 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-37750: smb: client: fix UAF in decryption with multichannel

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

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

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

smb: client: fix UAF in decryption with multichannel

After commit f7025d861694 ("smb: client: allocate crypto only for
primary server") and commit b0abcd65ec54 ("smb: client: fix UAF in
async decryption"), the channels started reusing AEAD TFM from primary
channel to perform synchronous decryption, but that can't done as
there could be multiple cifsd threads (one per channel) simultaneously
accessing it to perform decryption.

This fixes the following KASAN splat when running fstest generic/249
with 'vers=3.1.1,multichannel,max_channels=4,seal' against Windows
Server 2022:

BUG: KASAN: slab-use-after-free in gf128mul_4k_lle+0xba/0x110
Read of size 8 at addr ffff8881046c18a0 by task cifsd/986
CPU: 3 UID: 0 PID: 986 Comm: cifsd Not tainted 6.15.0-rc1 #1
PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-3.fc41
04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x5d/0x80
 print_report+0x156/0x528
 ? gf128mul_4k_lle+0xba/0x110
 ? __virt_addr_valid+0x145/0x300
 ? __phys_addr+0x46/0x90
 ? gf128mul_4k_lle+0xba/0x110
 kasan_report+0xdf/0x1a0
 ? gf128mul_4k_lle+0xba/0x110
 gf128mul_4k_lle+0xba/0x110
 ghash_update+0x189/0x210
 shash_ahash_update+0x295/0x370
 ? __pfx_shash_ahash_update+0x10/0x10
 ? __pfx_shash_ahash_update+0x10/0x10
 ? __pfx_extract_iter_to_sg+0x10/0x10
 ? ___kmalloc_large_node+0x10e/0x180
 ? __asan_memset+0x23/0x50
 crypto_ahash_update+0x3c/0xc0
 gcm_hash_assoc_remain_continue+0x93/0xc0
 crypt_message+0xe09/0xec0 [cifs]
 ? __pfx_crypt_message+0x10/0x10 [cifs]
 ? _raw_spin_unlock+0x23/0x40
 ? __pfx_cifs_readv_from_socket+0x10/0x10 [cifs]
 decrypt_raw_data+0x229/0x380 [cifs]
 ? __pfx_decrypt_raw_data+0x10/0x10 [cifs]
 ? __pfx_cifs_read_iter_from_socket+0x10/0x10 [cifs]
 smb3_receive_transform+0x837/0xc80 [cifs]
 ? __pfx_smb3_receive_transform+0x10/0x10 [cifs]
 ? __pfx___might_resched+0x10/0x10
 ? __pfx_smb3_is_transform_hdr+0x10/0x10 [cifs]
 cifs_demultiplex_thread+0x692/0x1570 [cifs]
 ? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
 ? rcu_is_watching+0x20/0x50
 ? rcu_lockdep_current_cpu_online+0x62/0xb0
 ? find_held_lock+0x32/0x90
 ? kvm_sched_clock_read+0x11/0x20
 ? local_clock_noinstr+0xd/0xd0
 ? trace_irq_enable.constprop.0+0xa8/0xe0
 ? __pfx_cifs_demultiplex_thread+0x10/0x10 [cifs]
 kthread+0x1fe/0x380
 ? kthread+0x10f/0x380
 ? __pfx_kthread+0x10/0x10
 ? local_clock_noinstr+0xd/0xd0
 ? ret_from_fork+0x1b/0x60
 ? local_clock+0x15/0x30
 ? lock_release+0x29b/0x390
 ? rcu_is_watching+0x20/0x50
 ? __pfx_kthread+0x10/0x10
 ret_from_fork+0x31/0x60
 ? __pfx_kthread+0x10/0x10
 ret_from_fork_asm+0x1a/0x30
 </TASK>

The Linux kernel CVE team has assigned CVE-2025-37750 to this issue.


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

	Issue introduced in 6.12 with commit b0abcd65ec545701b8793e12bc27dc98042b151a and fixed in 6.12.24 with commit aa5a1e4b882964eb79d5b5d1d1e8a1a5efbb1d15
	Issue introduced in 6.12 with commit b0abcd65ec545701b8793e12bc27dc98042b151a and fixed in 6.13.12 with commit e859b216d94668bc66330e61be201234f4413d1a
	Issue introduced in 6.12 with commit b0abcd65ec545701b8793e12bc27dc98042b151a and fixed in 6.14.3 with commit 950557922c1298464749c216d8763e97faf5d0a6
	Issue introduced in 6.12 with commit b0abcd65ec545701b8793e12bc27dc98042b151a and fixed in 6.15-rc2 with commit 9502dd5c7029902f4a425bf959917a5a9e7c0e50
	Issue introduced in 6.1.128 with commit bce966530fd5542bbb422cb45ecb775f7a1a6bc3
	Issue introduced in 6.6.57 with commit 0809fb86ad13b29e1d6d491364fc7ea4fb545995
	Issue introduced in 6.11.4 with commit 538c26d9bf70c90edc460d18c81008a4e555925a

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-2025-37750
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/cifsencrypt.c
	fs/smb/client/smb2ops.c
	fs/smb/client/smb2pdu.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/aa5a1e4b882964eb79d5b5d1d1e8a1a5efbb1d15
	https://git.kernel.org/stable/c/e859b216d94668bc66330e61be201234f4413d1a
	https://git.kernel.org/stable/c/950557922c1298464749c216d8763e97faf5d0a6
	https://git.kernel.org/stable/c/9502dd5c7029902f4a425bf959917a5a9e7c0e50