diff options
| author | Paolo Abeni <pabeni@redhat.com> | 2021-04-14 12:48:48 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-04-14 13:54:08 -0700 |
| commit | 17c3df7078e3742bd9e907f3006a9e3469383007 (patch) | |
| tree | c55a71950000467a7691fc7ace2b3c1fd82c70a4 /net/core/skbuff.c | |
| parent | 73d7de66aa3c76d90092649766278296042ba836 (diff) | |
skbuff: revert "skbuff: remove some unnecessary operation in skb_segment_list()"
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>
Diffstat (limited to 'net/core/skbuff.c')
| -rw-r--r-- | net/core/skbuff.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 3ad9e8425ab2..14010c0eec48 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3773,13 +3773,13 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, 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; @@ -3797,8 +3797,17 @@ struct sk_buff *skb_segment_list(struct sk_buff *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; @@ -3825,7 +3834,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, skb_gso_reset(skb); - skb->prev = nskb; + skb->prev = tail; if (skb_needs_linearize(skb, features) && __skb_linearize(skb)) |