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Message-ID: <2025061831-CVE-2025-38051-77da@gregkh>
Date: Wed, 18 Jun 2025 11:33:46 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38051: smb: client: Fix use-after-free in cifs_fill_dirent
From: Greg Kroah-Hartman <gregkh@...nel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
smb: client: Fix use-after-free in cifs_fill_dirent
There is a race condition in the readdir concurrency process, which may
access the rsp buffer after it has been released, triggering the
following KASAN warning.
==================================================================
BUG: KASAN: slab-use-after-free in cifs_fill_dirent+0xb03/0xb60 [cifs]
Read of size 4 at addr ffff8880099b819c by task a.out/342975
CPU: 2 UID: 0 PID: 342975 Comm: a.out Not tainted 6.15.0-rc6+ #240 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x53/0x70
print_report+0xce/0x640
kasan_report+0xb8/0xf0
cifs_fill_dirent+0xb03/0xb60 [cifs]
cifs_readdir+0x12cb/0x3190 [cifs]
iterate_dir+0x1a1/0x520
__x64_sys_getdents+0x134/0x220
do_syscall_64+0x4b/0x110
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f996f64b9f9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
f0 ff ff 0d f7 c3 0c 00 f7 d8 64 89 8
RSP: 002b:00007f996f53de78 EFLAGS: 00000207 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f996f53ecdc RCX: 00007f996f64b9f9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f996f53dea0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000207 R12: ffffffffffffff88
R13: 0000000000000000 R14: 00007ffc8cd9a500 R15: 00007f996f51e000
</TASK>
Allocated by task 408:
kasan_save_stack+0x20/0x40
kasan_save_track+0x14/0x30
__kasan_slab_alloc+0x6e/0x70
kmem_cache_alloc_noprof+0x117/0x3d0
mempool_alloc_noprof+0xf2/0x2c0
cifs_buf_get+0x36/0x80 [cifs]
allocate_buffers+0x1d2/0x330 [cifs]
cifs_demultiplex_thread+0x22b/0x2690 [cifs]
kthread+0x394/0x720
ret_from_fork+0x34/0x70
ret_from_fork_asm+0x1a/0x30
Freed by task 342979:
kasan_save_stack+0x20/0x40
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x60
__kasan_slab_free+0x37/0x50
kmem_cache_free+0x2b8/0x500
cifs_buf_release+0x3c/0x70 [cifs]
cifs_readdir+0x1c97/0x3190 [cifs]
iterate_dir+0x1a1/0x520
__x64_sys_getdents64+0x134/0x220
do_syscall_64+0x4b/0x110
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff8880099b8000
which belongs to the cache cifs_request of size 16588
The buggy address is located 412 bytes inside of
freed 16588-byte region [ffff8880099b8000, ffff8880099bc0cc)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x99b8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000
head: 0080000000000040 ffff888001e03400 0000000000000000 dead000000000001
head: 0000000000000000 0000000000010001 00000000f5000000 0000000000000000
head: 0080000000000003 ffffea0000266e01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff8880099b8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880099b8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880099b8180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880099b8200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880099b8280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
POC is available in the link [1].
The problem triggering process is as follows:
Process 1 Process 2
-----------------------------------------------------------------
cifs_readdir
/* file->private_data == NULL */
initiate_cifs_search
cifsFile = kzalloc(sizeof(struct cifsFileInfo), GFP_KERNEL);
smb2_query_dir_first ->query_dir_first()
SMB2_query_directory
SMB2_query_directory_init
cifs_send_recv
smb2_parse_query_directory
srch_inf->ntwrk_buf_start = (char *)rsp;
srch_inf->srch_entries_start = (char *)rsp + ...
srch_inf->last_entry = (char *)rsp + ...
srch_inf->smallBuf = true;
find_cifs_entry
/* if (cfile->srch_inf.ntwrk_buf_start) */
cifs_small_buf_release(cfile->srch_inf // free
cifs_readdir ->iterate_shared()
/* file->private_data != NULL */
find_cifs_entry
/* in while (...) loop */
smb2_query_dir_next ->query_dir_next()
SMB2_query_directory
SMB2_query_directory_init
cifs_send_recv
compound_send_recv
smb_send_rqst
__smb_send_rqst
rc = -ERESTARTSYS;
/* if (fatal_signal_pending()) */
goto out;
return rc
/* if (cfile->srch_inf.last_entry) */
cifs_save_resume_key()
cifs_fill_dirent // UAF
/* if (rc) */
return -ENOENT;
Fix this by ensuring the return code is checked before using pointers
from the srch_inf.
The Linux kernel CVE team has assigned CVE-2025-38051 to this issue.
Affected and fixed versions
===========================
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 5.4.294 with commit aee067e88d61eb72e966f094e4749c6b14e7008f
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 5.10.238 with commit a24c2f05ac3c5b0aaa539d9d913826d2643dfd0e
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 5.15.185 with commit 1b197931fbc821bc7e9e91bf619400db563e3338
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 6.1.141 with commit c8623231e0edfcccb7cc6add0288fa0f0594282f
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 6.6.93 with commit 73cadde98f67f76c5eba00ac0b72c453383cec8b
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 6.12.31 with commit 9bea368648ac46f8593a780760362e40291d22a9
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 6.14.9 with commit 9c9aafbacc183598f064902365e107b5e856531f
Issue introduced in 2.6.28 with commit a364bc0b37f14ffd66c1f982af42990a9d77fa43 and fixed in 6.15 with commit a7a8fe56e932a36f43e031b398aef92341bf5ea0
Issue introduced in 2.6.27.4 with commit 0f3da51e7046e2eb28992ba65c22d058f571356c
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-2025-38051
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/readdir.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/aee067e88d61eb72e966f094e4749c6b14e7008f
https://git.kernel.org/stable/c/a24c2f05ac3c5b0aaa539d9d913826d2643dfd0e
https://git.kernel.org/stable/c/1b197931fbc821bc7e9e91bf619400db563e3338
https://git.kernel.org/stable/c/c8623231e0edfcccb7cc6add0288fa0f0594282f
https://git.kernel.org/stable/c/73cadde98f67f76c5eba00ac0b72c453383cec8b
https://git.kernel.org/stable/c/9bea368648ac46f8593a780760362e40291d22a9
https://git.kernel.org/stable/c/9c9aafbacc183598f064902365e107b5e856531f
https://git.kernel.org/stable/c/a7a8fe56e932a36f43e031b398aef92341bf5ea0
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