From: Shyam Prasad N <sprasad@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
Reviewed-by: Paulo Alcantara (SUSE) <pc@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 724244cdb382 ("cifs: protect session channel fields with chan_lock")
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/cifs/connect.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1770,7 +1770,7 @@ out_err:
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
* 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
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,
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,
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);
