joel16/android_kernel_sony_msm8994
1
0
Fork 0
mirror of https://github.com/joel16/android_kernel_sony_msm8994.git synced 2024-11-26 21:51:03 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

ipv6: fix out of bound writes in __ip6_append_data()

Browse Source 
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>
This commit is contained in:
Eric Dumazet 2017-05-19 14:17:48 -07:00 committed by Olivier Karasangabo
parent 172b366d33
commit b2f9d4f533
No known key found for this signature in database
GPG Key ID: C5C93AF8ED1CCEB5
1 changed files with 8 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
net/ipv6/ip6_output.c
View File

@ -1364,6 +1364,11 @@ 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,
@ -1427,13 +1432,9 @@ 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;