From: Shyam Prasad N <sprasad@microsoft.com>
Date: Mon, 20 Feb 2023 13:02:11 +0000
Subject: [PATCH] cifs: lock chan_lock outside match_session
References: bsc#1012628
Patch-mainline: 6.2.9
Git-commit: 2f4e429c846972c8405951a9ff7a82aceeca7461
commit 2f4e429c846972c8405951a9ff7a82aceeca7461 upstream.
Coverity had rightly indicated a possible deadlock
due to chan_lock being done inside match_session.
All callers of match_* functions should pick up the
necessary locks and call them.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Cc: stable@vger.kernel.org
Fixes: 724244cdb382 ("cifs: protect session channel fields with chan_lock")
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/cifs/connect.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index b41e9472..6da2af97 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1770,7 +1770,7 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx,
return ERR_PTR(rc);
}
-/* this function must be called with ses_lock held */
+/* this function must be called with ses_lock and chan_lock held */
static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
if (ctx->sectype != Unspecified &&
@@ -1781,12 +1781,8 @@ static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
* If an existing session is limited to less channels than
* requested, it should not be reused
*/
- spin_lock(&ses->chan_lock);
- if (ses->chan_max < ctx->max_channels) {
- spin_unlock(&ses->chan_lock);
+ if (ses->chan_max < ctx->max_channels)
return 0;
- }
- spin_unlock(&ses->chan_lock);
switch (ses->sectype) {
case Kerberos:
@@ -1914,10 +1910,13 @@ cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
spin_unlock(&ses->ses_lock);
continue;
}
+ spin_lock(&ses->chan_lock);
if (!match_session(ses, ctx)) {
+ spin_unlock(&ses->chan_lock);
spin_unlock(&ses->ses_lock);
continue;
}
+ spin_unlock(&ses->chan_lock);
spin_unlock(&ses->ses_lock);
++ses->ses_count;
@@ -2743,6 +2742,7 @@ cifs_match_super(struct super_block *sb, void *data)
spin_lock(&tcp_srv->srv_lock);
spin_lock(&ses->ses_lock);
+ spin_lock(&ses->chan_lock);
spin_lock(&tcon->tc_lock);
if (!match_server(tcp_srv, ctx, dfs_super_cmp) ||
!match_session(ses, ctx) ||
@@ -2755,6 +2755,7 @@ cifs_match_super(struct super_block *sb, void *data)
rc = compare_mount_options(sb, mnt_data);
out:
spin_unlock(&tcon->tc_lock);
+ spin_unlock(&ses->chan_lock);
spin_unlock(&ses->ses_lock);
spin_unlock(&tcp_srv->srv_lock);
--
2.35.3