[v2] cifs: smb2pdu: Fix potential NULL pointer dereference

Message ID 20180403210039.GA28968@embeddedor.com
State New
Headers show
Series
  • [v2] cifs: smb2pdu: Fix potential NULL pointer dereference
Related show

Commit Message

Gustavo A. R. Silva April 3, 2018, 9 p.m.
tcon->ses is being dereferenced before it is null checked, hence
there is a potential null pointer dereference.

Fix this by moving the pointer dereference after tcon->ses has
been properly null checked.

Addresses-Coverity-ID: 1467426 ("Dereference before null check")
Fixes: 93012bf98416 ("cifs: add server->vals->header_preamble_size")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
---
Changes in v2:
 - Update subject.

 fs/cifs/smb2pdu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Aurélien Aptel April 4, 2018, 10:18 a.m. | #1
"Gustavo A. R. Silva" <garsilva@embeddedor.com> writes:
> tcon->ses is being dereferenced before it is null checked, hence
> there is a potential null pointer dereference.
>
> Fix this by moving the pointer dereference after tcon->ses has
> been properly null checked.
>
> Addresses-Coverity-ID: 1467426 ("Dereference before null check")
> Fixes: 93012bf98416 ("cifs: add server->vals->header_preamble_size")
> Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>

Reviewed-by: Aurelien Aptel <aaptel@suse.com>

Patch

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index f7741ce..e5ac474 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3454,7 +3454,7 @@  static int
 build_qfs_info_req(struct kvec *iov, struct cifs_tcon *tcon, int level,
 		   int outbuf_len, u64 persistent_fid, u64 volatile_fid)
 {
-	struct TCP_Server_Info *server = tcon->ses->server;
+	struct TCP_Server_Info *server;
 	int rc;
 	struct smb2_query_info_req *req;
 	unsigned int total_len;
@@ -3464,6 +3464,8 @@  build_qfs_info_req(struct kvec *iov, struct cifs_tcon *tcon, int level,
 	if ((tcon->ses == NULL) || (tcon->ses->server == NULL))
 		return -EIO;
 
+	server = tcon->ses->server;
+
 	rc = smb2_plain_req_init(SMB2_QUERY_INFO, tcon, (void **) &req,
 			     &total_len);
 	if (rc)