Commit b993ea46 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

atm: clip: prevent NULL deref in clip_push() 



Blamed commit missed that vcc_destroy_socket() calls
clip_push() with a NULL skb.

If clip_devs is NULL, clip_push() then crashes when reading
skb->truesize.

Fixes: 93a2014a ("atm: fix a UAF in lec_arp_clear_vccs()")
Reported-by: default avatar <syzbot+1316233c4c6803382a8b@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/netdev/68556f59.a00a0220.137b3.004e.GAE@google.com/T/#u


Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Gengming Liu <l.dmxcsnsbh@gmail.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 302251f1

net/atm/clip.c

+5 −6
Original line number Diff line number Diff line
@@ -193,12 +193,6 @@ static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb) 


	pr_debug("\n");



	if (!clip_devs) {

		atm_return(vcc, skb->truesize);

		kfree_skb(skb);

		return;

	}



	if (!skb) {

		pr_debug("removing VCC %p\n", clip_vcc);

		if (clip_vcc->entry)
@@ -208,6 +202,11 @@ static void clip_push(struct atm_vcc *vcc, struct sk_buff *skb) 
		return;

	}

	atm_return(vcc, skb->truesize);

	if (!clip_devs) {

		kfree_skb(skb);

		return;

	}



	skb->dev = clip_vcc->entry ? clip_vcc->entry->neigh->dev : clip_devs;

	/* clip_vcc->entry == NULL if we don't have an IP address yet */

	if (!skb->dev) {