5.10-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit b993ea46b3b601915ceaaf3c802adf11e7d6bac6 ]
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: 93a2014afbac ("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... 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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/atm/clip.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/net/atm/clip.c b/net/atm/clip.c index 294cb9efe3d38..511467bb7fe40 100644 --- a/net/atm/clip.c +++ b/net/atm/clip.c @@ -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) {