linux-cve-announce - CVE-2024-50047: smb: client: fix UAF in async decryption

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Message-ID: <2024102134-CVE-2024-50047-7a27@gregkh>
Date: Mon, 21 Oct 2024 21:39:53 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-50047: smb: client: fix UAF in async decryption

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

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

smb: client: fix UAF in async decryption

Doing an async decryption (large read) crashes with a
slab-use-after-free way down in the crypto API.

Reproducer:
    # mount.cifs -o ...,seal,esize=1 //srv/share /mnt
    # dd if=/mnt/largefile of=/dev/null
    ...
    [  194.196391] ==================================================================
    [  194.196844] BUG: KASAN: slab-use-after-free in gf128mul_4k_lle+0xc1/0x110
    [  194.197269] Read of size 8 at addr ffff888112bd0448 by task kworker/u77:2/899
    [  194.197707]
    [  194.197818] CPU: 12 UID: 0 PID: 899 Comm: kworker/u77:2 Not tainted 6.11.0-lku-00028-gfca3ca14a17a-dirty #43
    [  194.198400] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-3-gd478f380-prebuilt.qemu.org 04/01/2014
    [  194.199046] Workqueue: smb3decryptd smb2_decrypt_offload [cifs]
    [  194.200032] Call Trace:
    [  194.200191]  <TASK>
    [  194.200327]  dump_stack_lvl+0x4e/0x70
    [  194.200558]  ? gf128mul_4k_lle+0xc1/0x110
    [  194.200809]  print_report+0x174/0x505
    [  194.201040]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
    [  194.201352]  ? srso_return_thunk+0x5/0x5f
    [  194.201604]  ? __virt_addr_valid+0xdf/0x1c0
    [  194.201868]  ? gf128mul_4k_lle+0xc1/0x110
    [  194.202128]  kasan_report+0xc8/0x150
    [  194.202361]  ? gf128mul_4k_lle+0xc1/0x110
    [  194.202616]  gf128mul_4k_lle+0xc1/0x110
    [  194.202863]  ghash_update+0x184/0x210
    [  194.203103]  shash_ahash_update+0x184/0x2a0
    [  194.203377]  ? __pfx_shash_ahash_update+0x10/0x10
    [  194.203651]  ? srso_return_thunk+0x5/0x5f
    [  194.203877]  ? crypto_gcm_init_common+0x1ba/0x340
    [  194.204142]  gcm_hash_assoc_remain_continue+0x10a/0x140
    [  194.204434]  crypt_message+0xec1/0x10a0 [cifs]
    [  194.206489]  ? __pfx_crypt_message+0x10/0x10 [cifs]
    [  194.208507]  ? srso_return_thunk+0x5/0x5f
    [  194.209205]  ? srso_return_thunk+0x5/0x5f
    [  194.209925]  ? srso_return_thunk+0x5/0x5f
    [  194.210443]  ? srso_return_thunk+0x5/0x5f
    [  194.211037]  decrypt_raw_data+0x15f/0x250 [cifs]
    [  194.212906]  ? __pfx_decrypt_raw_data+0x10/0x10 [cifs]
    [  194.214670]  ? srso_return_thunk+0x5/0x5f
    [  194.215193]  smb2_decrypt_offload+0x12a/0x6c0 [cifs]

This is because TFM is being used in parallel.

Fix this by allocating a new AEAD TFM for async decryption, but keep
the existing one for synchronous READ cases (similar to what is done
in smb3_calc_signature()).

Also remove the calls to aead_request_set_callback() and
crypto_wait_req() since it's always going to be a synchronous operation.

The Linux kernel CVE team has assigned CVE-2024-50047 to this issue.


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

	Fixed in 6.6.57 with commit 0809fb86ad13
	Fixed in 6.11.4 with commit 538c26d9bf70
	Fixed in 6.12-rc1 with commit b0abcd65ec54

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-2024-50047
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
	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/0809fb86ad13b29e1d6d491364fc7ea4fb545995
	https://git.kernel.org/stable/c/538c26d9bf70c90edc460d18c81008a4e555925a
	https://git.kernel.org/stable/c/b0abcd65ec545701b8793e12bc27dc98042b151a