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net: hsr: check skb can contain struct hsr_ethhdr in fill_frame_info

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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@syzkaller.appspotmail.com
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Phillip Potter 2021-05-02 22:34:42 +01:00 committed by David S. Miller
parent f282df0391
commit 2e9f60932a
1 changed files with 4 additions and 0 deletions
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4
net/hsr/hsr_forward.c
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@ -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,