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    Subject[PATCH 5.11 019/329] fs: dlm: check on minimum msglen size
    Date
    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


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