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cifs: smb2pdu: Fix potential NULL pointer dereference

PATCH In review Gustavo A. R. Silva 2 participants 2 messages Apr 3, 2018 – Apr 4, 2018

Subsystems (2)
SMB client (CIFS) Kernel SMB3 server (ksmbd)
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Gustavo A. R. Silva

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PATCH v2 1/1 cifs: smb2pdu: Fix potential NULL pointer dereference

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 <[email protected]>

---
Changes in v2:
- Update subject.

 fs/cifs/smb2pdu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
fs/cifs/smb2pdu.c +3 -1
index f7741ce..e5ac474 100644
@@ -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)
Signature · 1 line
2.7.4
Reviewed-by on v2 1/1
#1 lore raw
Quoted 9 lines · Gustavo A. R. Silva

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 <[email protected]>
Reviewed-by Aurelien Aptel <[email protected]>
Signature · 4 lines
Aurélien Aptel / SUSE Labs Samba Team
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