Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorEric Dumazet <edumazet@google.com>2017-05-19 14:17:48 -0700
committerBen Hutchings <ben@decadent.org.uk>2017-06-05 21:17:25 +0100
commit55c51263ff43e3bf5deb1425f4221696f94db1be (patch)
treee5cee84a7b91f1b1e157dcf98a2f35149081e46b
parent53d48f98b800059504da76d12bf0074581aa0fe2 (diff)
ipv6: fix out of bound writes in __ip6_append_data()
commit 232cd35d0804cc241eb887bb8d4d9b3b9881c64a upstream. 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. 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> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--net/ipv6/ip6_output.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 9a9025098242..cbe7ddeb69c0 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1367,6 +1367,11 @@ 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,
@@ -1419,13 +1424,9 @@ 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;