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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alexander Aring <aahringo@redhat.com>,
        David Teigland <teigland@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.11 019/329] fs: dlm: check on minimum msglen size
Date:   Mon, 17 May 2021 15:58:50 +0200
Message-Id: <20210517140302.702411095@linuxfoundation.org>
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From: Alexander Aring <aahringo@redhat.com>

[ 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@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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