diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-05-19 14:17:48 -0700 |
|---|---|---|
| committer | Mister Oyster <oysterized@gmail.com> | 2017-06-02 13:18:23 +0200 |
| commit | b6d7263158bf76816a1c51e13f693217de62986b (patch) | |
| tree | bba1828d102dbca47e7d31730fa4b4f903359ac3 /net | |
| parent | 50020b79c35a259dbca1d37106d2f4dc9d932109 (diff) | |
ipv6: fix out of bound writes in __ip6_append_data()
Andrey Konovalov and idaifish@gmail.com reported crashes caused by
one skb shared_info being overwritten from __ip6_append_data()
Andrey program lead to following state :
copy -4200 datalen 2000 fraglen 2040
maxfraglen 2040 alloclen 2048 transhdrlen 0 offset 0 fraggap 6200
The skb_copy_and_csum_bits(skb_prev, maxfraglen, data + transhdrlen,
fraggap, 0); is overwriting skb->head and skb_shared_info
Since we apparently detect this rare condition too late, move the
code earlier to even avoid allocating skb and risking crashes.
Once again, many thanks to Andrey and syzkaller team.
Change-Id: Ieb39488dca91832154217fdac4a98246d8e407da
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: <idaifish@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv6/ip6_output.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 1ce7ea1f4..e121ce618 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1359,6 +1359,11 @@ alloc_new_skb: */ alloclen += sizeof(struct frag_hdr); + copy = datalen - transhdrlen - fraggap; + if (copy < 0) { + err = -EINVAL; + goto error; + } if (transhdrlen) { skb = sock_alloc_send_skb(sk, alloclen + hh_len, @@ -1410,13 +1415,9 @@ alloc_new_skb: data += fraggap; pskb_trim_unique(skb_prev, maxfraglen); } - copy = datalen - transhdrlen - fraggap; - - if (copy < 0) { - err = -EINVAL; - kfree_skb(skb); - goto error; - } else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) { + if (copy > 0 && + getfrag(from, data + transhdrlen, offset, + copy, fraggap, skb) < 0) { err = -EFAULT; kfree_skb(skb); goto error; |