1 files changed, 28 insertions, 19 deletions

diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index db0f27fd373b..818cc4dee0e2 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -132,15 +132,15 @@ static __u32 get_neg_ctxt_len(struct smb2_hdr *hdr, __u32 len,
 }
 
 int
-smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
+smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *server)
 {
 	struct smb2_hdr *shdr = (struct smb2_hdr *)buf;
 	struct smb2_pdu *pdu = (struct smb2_pdu *)shdr;
-	__u64 mid;
-	__u32 clc_len;  /* calculated length */
-	int command;
-	int pdu_size = sizeof(struct smb2_pdu);
 	int hdr_size = sizeof(struct smb2_hdr);
+	int pdu_size = sizeof(struct smb2_pdu);
+	int command;
+	__u32 calc_len; /* calculated length */
+	__u64 mid;
 
 	/*
 	 * Add function to do table lookup of StructureSize by command
@@ -154,7 +154,7 @@ smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
 
 		/* decrypt frame now that it is completely read in */
 		spin_lock(&cifs_tcp_ses_lock);
-		list_for_each_entry(iter, &srvr->smb_ses_list, smb_ses_list) {
+		list_for_each_entry(iter, &server->smb_ses_list, smb_ses_list) {
 			if (iter->Suid == le64_to_cpu(thdr->SessionId)) {
 				ses = iter;
 				break;
@@ -221,30 +221,33 @@ smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
 		}
 	}
 
-	clc_len = smb2_calc_size(buf, srvr);
+	calc_len = smb2_calc_size(buf, server);
+
+	/* For SMB2_IOCTL, OutputOffset and OutputLength are optional, so might
+	 * be 0, and not a real miscalculation */
+	if (command == SMB2_IOCTL_HE && calc_len == 0)
+		return 0;
 
-	if (shdr->Command == SMB2_NEGOTIATE)
-		clc_len += get_neg_ctxt_len(shdr, len, clc_len);
+	if (command == SMB2_NEGOTIATE_HE)
+		calc_len += get_neg_ctxt_len(shdr, len, calc_len);
 
-	if (len != clc_len) {
-		cifs_dbg(FYI, "Calculated size %u length %u mismatch mid %llu\n",
-			 clc_len, len, mid);
+	if (len != calc_len) {
 		/* create failed on symlink */
 		if (command == SMB2_CREATE_HE &&
 		    shdr->Status == STATUS_STOPPED_ON_SYMLINK)
 			return 0;
 		/* Windows 7 server returns 24 bytes more */
-		if (clc_len + 24 == len && command == SMB2_OPLOCK_BREAK_HE)
+		if (calc_len + 24 == len && command == SMB2_OPLOCK_BREAK_HE)
 			return 0;
 		/* server can return one byte more due to implied bcc[0] */
-		if (clc_len == len + 1)
+		if (calc_len == len + 1)
 			return 0;
 
 		/*
 		 * Some windows servers (win2016) will pad also the final
 		 * PDU in a compound to 8 bytes.
 		 */
-		if (((clc_len + 7) & ~7) == len)
+		if (((calc_len + 7) & ~7) == len)
 			return 0;
 
 		/*
@@ -253,12 +256,18 @@ smb2_check_message(char *buf, unsigned int len, struct TCP_Server_Info *srvr)
 		 * SMB2/SMB3 frame length (header + smb2 response specific data)
 		 * Some windows servers also pad up to 8 bytes when compounding.
 		 */
-		if (clc_len < len)
+		if (calc_len < len)
 			return 0;
 
-		pr_warn_once(
-			"srv rsp too short, len %d not %d. cmd:%d mid:%llu\n",
-			len, clc_len, command, mid);
+		/* Only log a message if len was really miscalculated */
+		if (unlikely(cifsFYI))
+			cifs_dbg(FYI, "Server response too short: calculated "
+				 "length %u doesn't match read length %u (cmd=%d, mid=%llu)\n",
+				 calc_len, len, command, mid);
+		else
+			pr_warn("Server response too short: calculated length "
+				"%u doesn't match read length %u (cmd=%d, mid=%llu)\n",
+				calc_len, len, command, mid);
 
 		return 1;
 	}