From: Shyam Prasad N sprasad@microsoft.com
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 --- 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);