From: Shaurya Rane Date: Wed, 26 Nov 2025 08:57:18 +0000 (+0530) Subject: net/sched: em_canid: fix uninit-value in em_canid_match X-Git-Tag: v6.18~19^2~3^2 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0c922106d7a58d106c6a5c52a741ae101cfaf088;p=thirdparty%2Flinux.git net/sched: em_canid: fix uninit-value in em_canid_match Use pskb_may_pull() to ensure a complete CAN frame is present in the linear data buffer before reading the CAN ID. 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 Link: https://patch.msgid.link/20251126085718.50808-1-ssranevjti@gmail.com Signed-off-by: Marc Kleine-Budde --- diff --git a/net/sched/em_canid.c b/net/sched/em_canid.c index 5337bc4627551..2d27f91d84413 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, CAN_MTU)) + return 0; + can_id = em_canid_get_id(skb); if (can_id & CAN_EFF_FLAG) {