[linux] 02/02: ipv6: fix out of bound writes in __ip6_append_data() (CVE-2017-9242)
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Thu Jun 1 07:08:45 UTC 2017
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carnil pushed a commit to branch sid
in repository linux.
commit 2502943c58ff305a8e09b8f804d8a49b5b57fff9
Author: Salvatore Bonaccorso <carnil at debian.org>
Date: Thu Jun 1 08:36:43 2017 +0200
ipv6: fix out of bound writes in __ip6_append_data() (CVE-2017-9242)
---
debian/changelog | 1 +
...-out-of-bound-writes-in-__ip6_append_data.patch | 67 ++++++++++++++++++++++
debian/patches/series | 1 +
3 files changed, 69 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index cc7b9bc..9757cfe 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -418,6 +418,7 @@ linux (4.9.30-1) UNRELEASED; urgency=medium
* ipv6/dccp: do not inherit ipv6_mc_list from parent (CVE-2017-9076
CVE-2017-9077)
* crypto: skcipher - Add missing API setkey checks (CVE-2017-9211)
+ * ipv6: fix out of bound writes in __ip6_append_data() (CVE-2017-9242)
-- Ben Hutchings <ben at decadent.org.uk> Mon, 08 May 2017 21:11:08 +0200
diff --git a/debian/patches/bugfix/all/ipv6-fix-out-of-bound-writes-in-__ip6_append_data.patch b/debian/patches/bugfix/all/ipv6-fix-out-of-bound-writes-in-__ip6_append_data.patch
new file mode 100644
index 0000000..3a2bf78
--- /dev/null
+++ b/debian/patches/bugfix/all/ipv6-fix-out-of-bound-writes-in-__ip6_append_data.patch
@@ -0,0 +1,67 @@
+From: Eric Dumazet <edumazet at google.com>
+Date: Fri, 19 May 2017 14:17:48 -0700
+Subject: ipv6: fix out of bound writes in __ip6_append_data()
+Origin: https://git.kernel.org/linus/232cd35d0804cc241eb887bb8d4d9b3b9881c64a
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-9242
+
+Andrey Konovalov and idaifish at 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 at google.com>
+Reported-by: Andrey Konovalov <andreyknvl at google.com>
+Tested-by: Andrey Konovalov <andreyknvl at google.com>
+Reported-by: <idaifish at gmail.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/ipv6/ip6_output.c | 15 ++++++++-------
+ 1 file changed, 8 insertions(+), 7 deletions(-)
+
+diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
+index d4a31be..bf8a58a 100644
+--- a/net/ipv6/ip6_output.c
++++ b/net/ipv6/ip6_output.c
+@@ -1466,6 +1466,11 @@ static int __ip6_append_data(struct sock *sk,
+ */
+ 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,
+@@ -1515,13 +1520,9 @@ static int __ip6_append_data(struct sock *sk,
+ 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;
+--
+2.1.4
+
diff --git a/debian/patches/series b/debian/patches/series
index 3a3e27b..cd9253c 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -110,6 +110,7 @@ bugfix/all/ipv6-prevent-overrun-when-parsing-v6-header-options.patch
bugfix/all/sctp-do-not-inherit-ipv6_-mc-ac-fl-_list-from-parent.patch
bugfix/all/ipv6-dccp-do-not-inherit-ipv6_mc_list-from-parent.patch
bugfix/all/crypto-skcipher-Add-missing-api-setkey-checks.patch
+bugfix/all/ipv6-fix-out-of-bound-writes-in-__ip6_append_data.patch
# Fix exported symbol versions
bugfix/ia64/revert-ia64-move-exports-to-definitions.patch
--
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