This is a note to let you know that I've just added the patch titled net: hsr: check skb can contain struct hsr_ethhdr in fill_frame_info to the 5.12-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: net-hsr-check-skb-can-contain-struct-hsr_ethhdr-in-f.patch and it can be found in the queue-5.12 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 885b82134cee5d30eb2cccda906bb4d29b279f9e Author: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Date: Sun May 2 22:34:42 2021 +0100 net: hsr: check skb can contain struct hsr_ethhdr in fill_frame_info [ Upstream commit 2e9f60932a2c19e8a11b4a69d419f107024b05a0 ] Check at start of fill_frame_info that the MAC header in the supplied skb is large enough to fit a struct hsr_ethhdr, as otherwise this is not a valid HSR frame. If it is too small, return an error which will then cause the callers to clean up the skb. Fixes a KMSAN-found uninit-value bug reported by syzbot at: https://syzkaller.appspot.com/bug?id=f7e9b601f1414f814f7602a82b6619a8d80bce3f Reported-by: syzbot+e267bed19bfc5478fb33@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Phillip Potter <phil@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c index b218e4594009..6852e9bccf5b 100644 --- a/net/hsr/hsr_forward.c +++ b/net/hsr/hsr_forward.c @@ -520,6 +520,10 @@ static int fill_frame_info(struct hsr_frame_info *frame, struct ethhdr *ethhdr; __be16 proto; + /* Check if skb contains hsr_ethhdr */ + if (skb->mac_len < sizeof(struct hsr_ethhdr)) + return -EINVAL; + memset(frame, 0, sizeof(*frame)); frame->is_supervision = is_supervision_frame(port->hsr, skb); frame->node_src = hsr_get_node(port, &hsr->node_db, skb,