FAILED: patch "[PATCH] smb: client: Fix match_session bug preventing session reuse" failed to apply to 6.12-stable tree

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 605b249ea96770ac4fac4b8510a99e0f8442be5e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025031652-undiluted-junction-7d5e@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 605b249ea96770ac4fac4b8510a99e0f8442be5e Mon Sep 17 00:00:00 2001
From: Henrique Carvalho <[email protected]>
Date: Tue, 11 Mar 2025 15:23:59 -0300
Subject: [PATCH] smb: client: Fix match_session bug preventing session reuse

Fix a bug in match_session() that can causes the session to not be reused in some cases.

Reproduction steps:

mount.cifs //server/share /mnt/a -o credentials=creds mount.cifs //server/share /mnt/b -o credentials=creds,sec=ntlmssp cat /proc/fs/cifs/DebugData | grep SessionId | wc -l

mount.cifs //server/share /mnt/b -o credentials=creds,sec=ntlmssp mount.cifs //server/share /mnt/a -o credentials=creds cat /proc/fs/cifs/DebugData | grep SessionId | wc -l

index f917de020dd5..73f93a35eedd 100644
@@ -1825,9 +1825,8 @@ static int match_session(struct cifs_ses *ses,
 			 struct smb3_fs_context *ctx,
 			 bool match_super)
 {
-	if (ctx->sectype != Unspecified &&
-	    ctx->sectype != ses->sectype)
-		return 0;
+	struct TCP_Server_Info *server = ses->server;
+	enum securityEnum ctx_sec, ses_sec;
 
 	if (!match_super && ctx->dfs_root_ses != ses->dfs_root_ses)
 		return 0;

@@ -1839,11 +1838,20 @@ static int match_session(struct cifs_ses *ses,
 	if (ses->chan_max < ctx->max_channels)
 		return 0;
 
-	switch (ses->sectype) {
+	ctx_sec = server->ops->select_sectype(server, ctx->sectype);
+	ses_sec = server->ops->select_sectype(server, ses->sectype);
+
+	if (ctx_sec != ses_sec)
+		return 0;
+
+	switch (ctx_sec) {
+	case IAKerb:
 	case Kerberos:
 		if (!uid_eq(ctx->cred_uid, ses->cred_uid))
 			return 0;
 		break;
+	case NTLMv2:
+	case RawNTLMSSP:
 	default:
 		/* NULL username means anonymous session */
 		if (ses->user_name == NULL) {

Fix a bug in match_session() that can causes the session to not be reused in some cases.

Reproduction steps:

mount.cifs //server/share /mnt/a -o credentials=creds mount.cifs //server/share /mnt/b -o credentials=creds,sec=ntlmssp cat /proc/fs/cifs/DebugData | grep SessionId | wc -l

mount.cifs //server/share /mnt/b -o credentials=creds,sec=ntlmssp mount.cifs //server/share /mnt/a -o credentials=creds cat /proc/fs/cifs/DebugData | grep SessionId | wc -l

---
 fs/smb/client/connect.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

index fb51cdf55206..e7ca893f0612 100644
@@ -1873,9 +1873,8 @@ static int match_session(struct cifs_ses *ses,
 			 struct smb3_fs_context *ctx,
 			 bool match_super)
 {
-	if (ctx->sectype != Unspecified &&
-	    ctx->sectype != ses->sectype)
-		return 0;
+	struct TCP_Server_Info *server = ses->server;
+	enum securityEnum ctx_sec, ses_sec;
 
 	if (!match_super && ctx->dfs_root_ses != ses->dfs_root_ses)
 		return 0;

@@ -1887,11 +1886,19 @@ static int match_session(struct cifs_ses *ses,
 	if (ses->chan_max < ctx->max_channels)
 		return 0;
 
-	switch (ses->sectype) {
+	ctx_sec = server->ops->select_sectype(server, ctx->sectype);
+	ses_sec = server->ops->select_sectype(server, ses->sectype);
+
+	if (ctx_sec != ses_sec)
+		return 0;
+
+	switch (ctx_sec) {
 	case Kerberos:
 		if (!uid_eq(ctx->cred_uid, ses->cred_uid))
 			return 0;
 		break;
+	case NTLMv2:
+	case RawNTLMSSP:
 	default:
 		/* NULL username means anonymous session */
 		if (ses->user_name == NULL) {

2.47.0

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 605b249ea96770ac4fac4b8510a99e0f8442be5e

Status in newer kernel trees:
6.13.y | Present (different SHA1: 4a133bda03ec)

Note: The patch differs from the upstream commit:
---
1: 605b249ea9677 ! 1: 7f254bc22751a smb: client: Fix match_session bug preventing session reuse
@@ Commit message

+ (cherry picked from commit 605b249ea96770ac4fac4b8510a99e0f8442be5e)

## fs/smb/client/connect.c ##
@@ fs/smb/client/connect.c: static int match_session(struct cifs_ses *ses,
@@ fs/smb/client/connect.c: static int match_session(struct cifs_ses *ses,
+ return 0;
+
+ switch (ctx_sec) {
-+ case IAKerb:
case Kerberos:
if (!uid_eq(ctx->cred_uid, ses->cred_uid))
return 0;
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.12.y       |  Success    |  Success   |