[PATCH 5.12 019/363] fs: dlm: check on minimum msglen size

From: Greg Kroah-Hartman
Date: Mon May 17 2021 - 10:05:47 EST


From: Alexander Aring <aahringo@xxxxxxxxxx>

[ Upstream commit 710176e8363f269c6ecd73d203973b31ace119d3 ]

This patch adds an additional check for minimum dlm header size which is
an invalid dlm message and signals a broken stream. A msglen field cannot
be less than the dlm header size because the field is inclusive header
lengths.

Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
Signed-off-by: David Teigland <teigland@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/dlm/midcomms.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index fde3a6afe4be..0bedfa8606a2 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -49,9 +49,10 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
* cannot deliver this message to upper layers
*/
msglen = get_unaligned_le16(&hd->h_length);
- if (msglen > DEFAULT_BUFFER_SIZE) {
- log_print("received invalid length header: %u, will abort message parsing",
- msglen);
+ if (msglen > DEFAULT_BUFFER_SIZE ||
+ msglen < sizeof(struct dlm_header)) {
+ log_print("received invalid length header: %u from node %d, will abort message parsing",
+ msglen, nodeid);
return -EBADMSG;
}

--
2.30.2