[PATCH][CIFS] fix missing spinlock around update to ses->status

[PATCH][CIFS] fix missing spinlock around update to ses->status

[Steve French]

[-- Attachment #1: Type: text/plain, Size: 1935 bytes --]

In the other places where we update ses->status we protect the
updates via GlobalMid_Lock. So to be consistent add the same
locking around it in cifs_put_smb_ses where it was missing.

Addresses-Coverity: 1268904 ("Data race condition")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifsglob.h | 3 ++-
 fs/cifs/connect.c  | 5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 988346904fd0..fc6b08e5ebbc 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -887,7 +887,7 @@ struct cifs_ses {
  struct mutex session_mutex;
  struct TCP_Server_Info *server; /* pointer to server info */
  int ses_count; /* reference counter */
- enum statusEnum status;
+ enum statusEnum status;  /* updates protected by GlobalMid_Lock */
  unsigned overrideSecFlg;  /* if non-zero override global sec flags */
  char *serverOS; /* name of operating system underlying server */
  char *serverNOS; /* name of network operating system of server */
@@ -1785,6 +1785,7 @@ require use of the stronger protocol */
  * list operations on pending_mid_q and oplockQ
  *      updates to XID counters, multiplex id  and SMB sequence numbers
  *      list operations on global DnotifyReqList
+ *      updates to ses->status
  *  tcp_ses_lock protects:
  * list operations on tcp and SMB session lists
  *  tcon->open_file_lock protects the list of open files hanging off the tcon
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c8079376d294..5d269f583dac 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1598,9 +1598,12 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
  spin_unlock(&cifs_tcp_ses_lock);
  return;
  }
+ spin_unlock(&cifs_tcp_ses_lock);
+
+ spin_lock(&GlobalMid_Lock);
  if (ses->status == CifsGood)
  ses->status = CifsExiting;
- spin_unlock(&cifs_tcp_ses_lock);
+ spin_unlock(&GlobalMid_Lock);

  cifs_free_ipc(ses);


-- 
Thanks,

Steve

[-- Attachment #2: 0001-cifs-fix-missing-spinlock-around-update-to-ses-statu.patch --]
[-- Type: text/x-patch, Size: 2161 bytes --]

From 591071fab232bcde3584ad1fd1ed0f6fdc2fcdb5 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Thu, 24 Jun 2021 15:28:04 -0500
Subject: [PATCH] cifs: fix missing spinlock around update to ses->status

In the other places where we update ses->status we protect the
updates via GlobalMid_Lock. So to be consistent add the same
locking around it in cifs_put_smb_ses where it was missing.

Addresses-Coverity: 1268904 ("Data race condition")
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/cifsglob.h | 3 ++-
 fs/cifs/connect.c  | 5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 988346904fd0..fc6b08e5ebbc 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -887,7 +887,7 @@ struct cifs_ses {
 	struct mutex session_mutex;
 	struct TCP_Server_Info *server;	/* pointer to server info */
 	int ses_count;		/* reference counter */
-	enum statusEnum status;
+	enum statusEnum status;  /* updates protected by GlobalMid_Lock */
 	unsigned overrideSecFlg;  /* if non-zero override global sec flags */
 	char *serverOS;		/* name of operating system underlying server */
 	char *serverNOS;	/* name of network operating system of server */
@@ -1785,6 +1785,7 @@ require use of the stronger protocol */
  *	list operations on pending_mid_q and oplockQ
  *      updates to XID counters, multiplex id  and SMB sequence numbers
  *      list operations on global DnotifyReqList
+ *      updates to ses->status
  *  tcp_ses_lock protects:
  *	list operations on tcp and SMB session lists
  *  tcon->open_file_lock protects the list of open files hanging off the tcon
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c8079376d294..5d269f583dac 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1598,9 +1598,12 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
+
+	spin_lock(&GlobalMid_Lock);
 	if (ses->status == CifsGood)
 		ses->status = CifsExiting;
-	spin_unlock(&cifs_tcp_ses_lock);
+	spin_unlock(&GlobalMid_Lock);
 
 	cifs_free_ipc(ses);
 
-- 
2.30.2