the commit
1ddc3229ad3c ("skbuff: remove some unnecessary operation
in skb_segment_list()") introduces an issue very similar to the
one already fixed by commit
53475c5dd856 ("net: fix use-after-free when
UDP GRO with shared fraglist").
If the GSO skb goes though skb_clone() and pskb_expand_head() before
entering skb_segment_list(), the latter will unshare the frag_list
skbs and will release the old list. With the reverted commit in place,
when skb_segment_list() completes, skb->next points to the just
released list, and later on the kernel will hit UaF.
Note that since commit
e0e3070a9bc9 ("udp: properly complete L4 GRO
over UDP tunnel packet") the critical scenario can be reproduced also
receiving UDP over vxlan traffic with:
NIC (NETIF_F_GRO_FRAGLIST enabled) -> vxlan -> UDP sink
Attaching a packet socket to the NIC will cause skb_clone() and the
tunnel decapsulation will call pskb_expand_head().
Fixes:
1ddc3229ad3c ("skbuff: remove some unnecessary operation in skb_segment_list()")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
unsigned int tnl_hlen = skb_tnl_header_len(skb);
unsigned int delta_truesize = 0;
unsigned int delta_len = 0;
+ struct sk_buff *tail = NULL;
struct sk_buff *nskb, *tmp;
int err;
skb_push(skb, -skb_network_offset(skb) + offset);
skb_shinfo(skb)->frag_list = NULL;
- skb->next = list_skb;
do {
nskb = list_skb;
}
}
- if (unlikely(err))
+ if (!tail)
+ skb->next = nskb;
+ else
+ tail->next = nskb;
+
+ if (unlikely(err)) {
+ nskb->next = list_skb;
goto err_linearize;
+ }
+
+ tail = nskb;
delta_len += nskb->len;
delta_truesize += nskb->truesize;
skb_gso_reset(skb);
- skb->prev = nskb;
+ skb->prev = tail;
if (skb_needs_linearize(skb, features) &&
__skb_linearize(skb))