[PATCH] cifs: verify signature only for valid responses

[Enzo Matsumiya <ematsumiya@suse.de>]

The signature check will always fail for a response with SMB2
Status == STATUS_END_OF_FILE, so skip the verification of those.

Also, in async IO, it doesn't make sense to verify the signature
of an unsuccessful read (rdata->result != 0), as the data is
probably corrupt/inconsistent/incomplete. Verify only the responses
of successful reads.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/smb2pdu.c       | 4 ++--
 fs/cifs/smb2transport.c | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 6352ab32c7e7..9ae25ba909f5 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -4144,8 +4144,8 @@ smb2_readv_callback(struct mid_q_entry *mid)
 	case MID_RESPONSE_RECEIVED:
 		credits.value = le16_to_cpu(shdr->CreditRequest);
 		credits.instance = server->reconnect_instance;
-		/* result already set, check signature */
-		if (server->sign && !mid->decrypted) {
+		/* check signature only if read was successful */
+		if (server->sign && !mid->decrypted && rdata->result == 0) {
 			int rc;
 
 			rc = smb2_verify_signature(&rqst, server);
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 1a5fc3314dbf..37c7ed2f1984 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -668,6 +668,7 @@ smb2_verify_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 	if ((shdr->Command == SMB2_NEGOTIATE) ||
 	    (shdr->Command == SMB2_SESSION_SETUP) ||
 	    (shdr->Command == SMB2_OPLOCK_BREAK) ||
+	    (shdr->Status == STATUS_END_OF_FILE) ||
 	    server->ignore_signature ||
 	    (!server->session_estab))
 		return 0;
-- 
2.35.3