dlm: dlm_process_incoming_buffer() fixes

* check that length is large enough to cover the non-variable part of message or
  rcom resp. (after checking that it's large enough to cover the header, of
  course).

* kill more pointless casts

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 20 insertions, 13 deletions

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index e69926e984d..07ac709f3ed 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -61,9 +61,9 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
 	union {
 		unsigned char __buf[DLM_INBUF_LEN];
 		/* this is to force proper alignment on some arches */
-		struct dlm_header dlm;
+		union dlm_packet p;
 	} __tmp;
-	struct dlm_header *msg = &__tmp.dlm;
+	union dlm_packet *p = &__tmp.p;
 	int ret = 0;
 	int err = 0;
 	uint16_t msglen;
@@ -75,15 +75,22 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
 		   message may wrap around the end of the buffer back to the
 		   start, so we need to use a temp buffer and copy_from_cb. */
 
-		copy_from_cb(msg, base, offset, sizeof(struct dlm_header),
+		copy_from_cb(p, base, offset, sizeof(struct dlm_header),
 			     limit);
 
-		msglen = le16_to_cpu(msg->h_length);
-		lockspace = msg->h_lockspace;
+		msglen = le16_to_cpu(p->header.h_length);
+		lockspace = p->header.h_lockspace;
 
 		err = -EINVAL;
 		if (msglen < sizeof(struct dlm_header))
 			break;
+		if (p->header.h_cmd == DLM_MSG) {
+			if (msglen < sizeof(struct dlm_message))
+				break;
+		} else {
+			if (msglen < sizeof(struct dlm_rcom))
+				break;
+		}
 		err = -E2BIG;
 		if (msglen > dlm_config.ci_buffer_size) {
 			log_print("message size %d from %d too big, buf len %d",
@@ -104,26 +111,26 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
 		   in the buffer on the stack (which should work for most
 		   ordinary messages). */
 
-		if (msglen > DLM_INBUF_LEN && msg == &__tmp.dlm) {
-			msg = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
-			if (msg == NULL)
+		if (msglen > sizeof(__tmp) && p == &__tmp.p) {
+			p = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
+			if (p == NULL)
 				return ret;
 		}
 
-		copy_from_cb(msg, base, offset, msglen, limit);
+		copy_from_cb(p, base, offset, msglen, limit);
 
-		BUG_ON(lockspace != msg->h_lockspace);
+		BUG_ON(lockspace != p->header.h_lockspace);
 
 		ret += msglen;
 		offset += msglen;
 		offset &= (limit - 1);
 		len -= msglen;
 
-		dlm_receive_buffer(msg, nodeid);
+		dlm_receive_buffer(p, nodeid);
 	}
 
-	if (msg != &__tmp.dlm)
-		kfree(msg);
+	if (p != &__tmp.p)
+		kfree(p);
 
 	return err ? err : ret;
 }