This is a note to let you know that I've just added the patch titled sctp: add size validation when walking chunks to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sctp-add-size-validation-when-walking-chunks.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 69c8aa0bcfb2bf7d1d02c0942356a165df2958a3 Author: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Date: Mon Jun 28 16:13:42 2021 -0300 sctp: add size validation when walking chunks [ Upstream commit 50619dbf8db77e98d821d615af4f634d08e22698 ] The first chunk in a packet is ensured to be present at the beginning of sctp_rcv(), as a packet needs to have at least 1 chunk. But the second one, may not be completely available and ch->length can be over uninitialized memory. Fix here is by only trying to walk on the next chunk if there is enough to hold at least the header, and then proceed with the ch->length validation that is already there. Reported-by: Ilja Van Sprundel <ivansprundel@xxxxxxxxxxxx> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/sctp/input.c b/net/sctp/input.c index e17c8359571c..203aaefd8d04 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -1204,7 +1204,7 @@ static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net, ch = (struct sctp_chunkhdr *)ch_end; chunk_num++; - } while (ch_end < skb_tail_pointer(skb)); + } while (ch_end + sizeof(*ch) < skb_tail_pointer(skb)); return asoc; }