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atm: clip: prevent NULL deref in clip_push()

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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: 93a2014afb ("atm: fix a UAF in lec_arp_clear_vccs()")
Reported-by: syzbot+1316233c4c6803382a8b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68556f59.a00a0220.137b3.004e.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Gengming Liu <l.dmxcsnsbh@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2025-06-20 14:28:44 +00:00 • committed by David S. Miller
parent 302251f1fd
commit b993ea46b3
1 changed files with 5 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

11
net/atm/clip.c
View file

@ -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) {