From: Shaurya Rane Use pskb_may_pull() to ensure the CAN ID is accessible in the linear data buffer before reading it. A simple skb->len check is insufficient because it only verifies the total data length but does not guarantee the data is present in skb->data (it could be in fragments). pskb_may_pull() both validates the length and pulls fragmented data into the linear buffer if necessary, making it safe to directly access skb->data. Reported-by: syzbot+5d8269a1e099279152bc@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=5d8269a1e099279152bc Fixes: f057bbb6f9ed ("net: em_canid: Ematch rule to match CAN frames according to their identifiers") Signed-off-by: Shaurya Rane --- v2: Use pskb_may_pull() instead of skb->len check to properly handle fragmented skbs (Eric Dumazet) --- net/sched/em_canid.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sched/em_canid.c b/net/sched/em_canid.c index 5337bc462755..2214b548fab8 100644 --- a/net/sched/em_canid.c +++ b/net/sched/em_canid.c @@ -99,6 +99,9 @@ static int em_canid_match(struct sk_buff *skb, struct tcf_ematch *m, int i; const struct can_filter *lp; + if (!pskb_may_pull(skb, sizeof(canid_t))) + return 0; + can_id = em_canid_get_id(skb); if (can_id & CAN_EFF_FLAG) { -- 2.34.1