2018-04-03 21:02:10

by Gustavo A. R. Silva

[permalink] [raw]
Subject: [PATCH v2] 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(-)

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)
--
2.7.4



2018-04-04 10:19:28

by Aurélien Aptel

[permalink] [raw]
Subject: Re: [PATCH v2] cifs: smb2pdu: Fix potential NULL pointer dereference

"Gustavo A. R. Silva" <[email protected]> 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 <[email protected]>

Reviewed-by: Aurelien Aptel <[email protected]>

--
Aurélien Aptel / SUSE Labs Samba Team
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