cifs: fix dereference on ses before it is null checked

The assignment of pointer server dereferences pointer ses, however,
this dereference occurs before ses is null checked and hence we
have a potential null pointer dereference.  Fix this by only
dereferencing ses after it has been null checked.

Addresses-Coverity: ("Dereference before null check")
Fixes: 2808c6639104 ("cifs: add new debugging macro cifs_server_dbg")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index dbc6ef50dd45de7c778cd508e43c6d5019aaeda8..0e92983de0b70b7d7c407d0a9154c27c7b57b7d5 100644 (file)
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -2759,8 +2759,10 @@ SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
        else
                return -EIO;
 
+       if (!ses)
+               return -EIO;
        server = ses->server;
-       if (!ses || !(server))
+       if (!server)
                return -EIO;
 
        if (smb3_encryption_required(tcon))
@@ -3058,13 +3060,16 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
        int rc = 0;
        int resp_buftype = CIFS_NO_BUFFER;
        struct cifs_ses *ses = tcon->ses;
-       struct TCP_Server_Info *server = ses->server;
+       struct TCP_Server_Info *server;
        int flags = 0;
        bool allocated = false;
 
        cifs_dbg(FYI, "Query Info\n");
 
-       if (!ses || !(server))
+       if (!ses)
+               return -EIO;
+       server = ses->server;
+       if (!server)
                return -EIO;
 
        if (smb3_encryption_required(tcon))

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 0d60bd2f4dcaefe0a46e85bb5609ddc2485ee750..a90bd4d75b4dbf5d2350efdfa1630ac0b130e53f 100644 (file)
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -1242,12 +1242,13 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
        struct kvec iov = { .iov_base = in_buf, .iov_len = len };
        struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };
        struct cifs_credits credits = { .value = 1, .instance = 0 };
-       struct TCP_Server_Info *server = ses->server;
+       struct TCP_Server_Info *server;
 
        if (ses == NULL) {
                cifs_dbg(VFS, "Null smb session\n");
                return -EIO;
        }
+       server = ses->server;
        if (server == NULL) {
                cifs_dbg(VFS, "Null tcp session\n");
                return -EIO;