[PATCH RFC 5.15] smb: client: fix potential UAF in cifs_stats_proc_write()

[PATCH RFC 5.15] smb: client: fix potential UAF in cifs_stats_proc_write()

[Xiangyu Chen]

From: Paulo Alcantara <pc@manguebit.com>

commit d3da25c5ac84430f89875ca7485a3828150a7e0a upstream.

Skip sessions that are being teared down (status == SES_EXITING) to
avoid UAF.

Cc: stable@vger.kernel.org
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
[ cifs_debug.c was moved from fs/cifs to fs/smb/client since
38c8a9a52082 ("smb: move client and server files to common directory fs/smb").
The cifs_ses_exiting() was introduced to cifs_debug.c since
ca545b7f0823 ("smb: client: fix potential UAF in cifs_debug_files_proc_show()").
and the SES_EXITING in cifs_ses_exiting() instead of CifsExiting since
dd3cd8709ed5 ("cifs: use new enum for ses_status").
The ses_lock in cifs_ses_exiting() was introduced in commmit d7d7a66aacd6
("cifs: avoid use of global locks for high contention data"), on 5.15/5.10,
there is a global lock take care of ses->status.
So use "if (ses->status == CifsExiting)" instead of "if (cifs_ses_exiting(ses))" ]
Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
---
Try to merge commit d3da25c5ac84430f89875ca7485a3828150a7e0a to 5.15
Verified the code compile on linux 5.15
---
 fs/cifs/cifs_debug.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index e7501533c2ec..ce02cc71e117 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -528,6 +528,8 @@ static ssize_t cifs_stats_proc_write(struct file *file,
 			list_for_each(tmp2, &server->smb_ses_list) {
 				ses = list_entry(tmp2, struct cifs_ses,
 						 smb_ses_list);
+				if (ses->status == CifsExiting)
+					continue;
 				list_for_each(tmp3, &ses->tcon_list) {
 					tcon = list_entry(tmp3,
 							  struct cifs_tcon,
-- 
2.25.1

Re: [PATCH RFC 5.15] smb: client: fix potential UAF in cifs_stats_proc_write()

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: d3da25c5ac84430f89875ca7485a3828150a7e0a

WARNING: Author mismatch between patch and upstream commit:
Backport author: Xiangyu Chen<xiangyu.chen@eng.windriver.com>
Commit author: Paulo Alcantara<pc@manguebit.com>

Status in newer kernel trees:
6.13.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: cf03020c56d3)
6.1.y | Present (different SHA1: 8fefd166fcb3)

Note: The patch differs from the upstream commit:
---
1:  d3da25c5ac844 < -:  ------------- smb: client: fix potential UAF in cifs_stats_proc_write()
-:  ------------- > 1:  b543f15d675d5 smb: client: fix potential UAF in cifs_stats_proc_write()
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-5.15.y       |  Success    |  Success   |