smb: client: fix deadlock in smb2_find_smb_tcon()

ematsumiya · smfrench · commit 02c418774f76 · 2024-06-07T01:05:07.000-05:00
Unlock cifs_tcp_ses_lock before calling cifs_put_smb_ses() to avoid such
deadlock.

Cc: stable@vger.kernel.org
Signed-off-by: Enzo Matsumiya &lt;ematsumiya@suse.de&gt;
Reviewed-by: Shyam Prasad N &lt;sprasad@microsoft.com&gt;
Reviewed-by: Paulo Alcantara (Red Hat) &lt;pc@manguebit.com&gt;
Signed-off-by: Steve French &lt;stfrench@microsoft.com&gt;
diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
@@ -216,8 +216,8 @@ smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32  tid)
 	}
 	tcon = smb2_find_smb_sess_tcon_unlocked(ses, tid);
 	if (!tcon) {
-		cifs_put_smb_ses(ses);
 		spin_unlock(&cifs_tcp_ses_lock);
+		cifs_put_smb_ses(ses);
 		return NULL;
 	}
 	spin_unlock(&cifs_tcp_ses_lock);

Original file line number	Diff line number	Diff line change
`@@ -216,8 +216,8 @@ smb2_find_smb_tcon(struct TCP_Server_Info *server, __u64 ses_id, __u32 tid)`
`216`	`216`	`}`
`217`	`217`	`tcon = smb2_find_smb_sess_tcon_unlocked(ses, tid);`
`218`	`218`	`if (!tcon) {`
`219`		`- cifs_put_smb_ses(ses);`
`220`	`219`	`spin_unlock(&cifs_tcp_ses_lock);`
	`220`	`+ cifs_put_smb_ses(ses);`
`221`	`221`	`return NULL;`
`222`	`222`	`}`
`223`	`223`	`spin_unlock(&cifs_tcp_ses_lock);`