FAILED: patch "[PATCH] smb: client: Fix use-after-free in cifs_fill_dirent" failed to apply to 5.4-stable tree
Subsystems (2)
[email protected]
maintainerThe patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x a7a8fe56e932a36f43e031b398aef92341bf5ea0
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025052437-platform-elastic-f5d2@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a7a8fe56e932a36f43e031b398aef92341bf5ea0 Mon Sep 17 00:00:00 2001
From: Wang Zhaolong <[email protected]>
Date: Fri, 16 May 2025 17:12:55 +0800
Subject: [PATCH] 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.
Fixes a364bc0b37f1 ("[CIFS] fix saving of resume key before CIFSFindNext")
Reviewed-by Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by Wang Zhaolong <[email protected]>
Signed-off-by Steve French <[email protected]>
fs/smb/client/readdir.c +2 -2
@@ -756,11 +756,11 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, rc = server->ops->query_dir_next (xid, tcon, &cfile->fid, search_flags, &cfile->srch_inf); +if (rc) +return -ENOENT ;/* FindFirst/Next set last_entry to NULL on malformed reply */ if (cfile->srch_inf.last_entry)cifs_save_resume_key (cfile->srch_inf.last_entry, cfile); -if (rc) -return -ENOENT ; }if (index_to_find < cfile->srch_inf.index_of_last_entry) {/* we found the buffer that contains the entry */
PATCH 1/2 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.
Fixes a364bc0b37f1 ("[CIFS] fix saving of resume key before CIFSFindNext")
Reviewed-by Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by Wang Zhaolong <[email protected]>
Signed-off-by Steve French <[email protected]>
(cherry picked from commit a7a8fe56e932a36f43e031b398aef92341bf5ea0)
Signed-off-by Wang Zhaolong <[email protected]>
--- fs/cifs/readdir.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
fs/cifs/readdir.c +2 -2
@@ -642,15 +642,15 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos, (rc == 0) && !cfile->srch_inf.endOfSearch) {cifs_dbg (FYI ,"calling findnext2\n" ); rc = server->ops->query_dir_next (xid, tcon, &cfile->fid, search_flags, &cfile->srch_inf); +if (rc) +return -ENOENT ;/* FindFirst/Next set last_entry to NULL on malformed reply */ if (cfile->srch_inf.last_entry)cifs_save_resume_key (cfile->srch_inf.last_entry, cfile); -if (rc) -return -ENOENT ; }if (index_to_find < cfile->srch_inf.index_of_last_entry) {/* we found the buffer that contains the entry */ /* scan and find it */ int i;
Signature · 1 line
2.34.3
PATCH 2/2 smb: client: Reset all search buffer pointers when releasing buffer
Multiple pointers in struct cifs_search_info (ntwrk_buf_start, srch_entries_start, and last_entry) point to the same allocated buffer. However, when freeing this buffer, only ntwrk_buf_start was set to NULL, while the other pointers remained pointing to freed memory.
This is defensive programming to prevent potential issues with stale pointers. While the active UAF vulnerability is fixed by the previous patch, this change ensures consistent pointer state and more robust error handling.
Signed-off-by Wang Zhaolong <[email protected]>
Reviewed-by Paulo Alcantara (Red Hat) <[email protected]>
Signed-off-by Steve French <[email protected]>
(cherry picked from commit e48f9d849bfdec276eebf782a84fd4dfbe1c14c0)
Signed-off-by Wang Zhaolong <[email protected]>
--- fs/cifs/readdir.c | 3 +++ 1 file changed, 3 insertions(+)
fs/cifs/readdir.c +3 -0
@@ -619,11 +619,14 @@ find_cifs_entry(const unsigned int xid, struct cifs_tcon *tcon, loff_t pos,cifs_small_buf_release (cfile->srch_inf. ntwrk_buf_start); else cifs_buf_release(cfile->srch_inf. ntwrk_buf_start); +/* Reset all pointers to the network buffer to prevent stale references */ cfile->srch_inf.ntwrk_buf_start =NULL ; + cfile->srch_inf.srch_entries_start =NULL ; + cfile->srch_inf.last_entry =NULL ; } rc =initiate_cifs_search (xid, file);if (rc) {cifs_dbg (FYI ,"error %d reinitiating a search on rewind\n" , rc);
Signature · 1 line
2.34.3