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https://github.com/Divested-Mobile/DivestOS-Build.git
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64 lines
2.1 KiB
Diff
64 lines
2.1 KiB
Diff
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From 232cd35d0804cc241eb887bb8d4d9b3b9881c64a Mon Sep 17 00:00:00 2001
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From: Eric Dumazet <edumazet@google.com>
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Date: Fri, 19 May 2017 14:17:48 -0700
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Subject: [PATCH] ipv6: fix out of bound writes in __ip6_append_data()
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Andrey Konovalov and idaifish@gmail.com reported crashes caused by
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one skb shared_info being overwritten from __ip6_append_data()
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Andrey program lead to following state :
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copy -4200 datalen 2000 fraglen 2040
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maxfraglen 2040 alloclen 2048 transhdrlen 0 offset 0 fraggap 6200
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The skb_copy_and_csum_bits(skb_prev, maxfraglen, data + transhdrlen,
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fraggap, 0); is overwriting skb->head and skb_shared_info
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Since we apparently detect this rare condition too late, move the
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code earlier to even avoid allocating skb and risking crashes.
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Once again, many thanks to Andrey and syzkaller team.
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Signed-off-by: Eric Dumazet <edumazet@google.com>
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Reported-by: Andrey Konovalov <andreyknvl@google.com>
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Tested-by: Andrey Konovalov <andreyknvl@google.com>
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Reported-by: <idaifish@gmail.com>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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net/ipv6/ip6_output.c | 15 ++++++++-------
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1 file changed, 8 insertions(+), 7 deletions(-)
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diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
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index d4a31becbd25d..bf8a58a1c32d8 100644
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--- a/net/ipv6/ip6_output.c
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+++ b/net/ipv6/ip6_output.c
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@@ -1466,6 +1466,11 @@ static int __ip6_append_data(struct sock *sk,
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*/
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alloclen += sizeof(struct frag_hdr);
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+ copy = datalen - transhdrlen - fraggap;
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+ if (copy < 0) {
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+ err = -EINVAL;
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+ goto error;
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+ }
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if (transhdrlen) {
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skb = sock_alloc_send_skb(sk,
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alloclen + hh_len,
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@@ -1515,13 +1520,9 @@ static int __ip6_append_data(struct sock *sk,
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data += fraggap;
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pskb_trim_unique(skb_prev, maxfraglen);
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}
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- copy = datalen - transhdrlen - fraggap;
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-
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- if (copy < 0) {
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- err = -EINVAL;
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- kfree_skb(skb);
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- goto error;
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- } else if (copy > 0 && getfrag(from, data + transhdrlen, offset, copy, fraggap, skb) < 0) {
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+ if (copy > 0 &&
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+ getfrag(from, data + transhdrlen, offset,
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+ copy, fraggap, skb) < 0) {
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err = -EFAULT;
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kfree_skb(skb);
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goto error;
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