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ipv4: keep skb->dst around in presence of IP options (CVE-2017-5970)

This commit is contained in:
Salvatore Bonaccorso 2017-02-15 11:49:34 +01:00
parent 4e5e705c5f
commit 9e381d5c13
3 changed files with 49 additions and 0 deletions
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1
debian/changelog vendored
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@ -197,6 +197,7 @@ linux (4.9.9-1) UNRELEASED; urgency=medium
[ Salvatore Bonaccorso ]
* IB/rxe: Fix mem_check_range integer overflow (CVE-2016-8636)
* selinux: fix off-by-one in setprocattr (CVE-2017-2618)
* ipv4: keep skb->dst around in presence of IP options (CVE-2017-5970)
-- Ben Hutchings <ben@decadent.org.uk> Fri, 27 Jan 2017 18:14:31 +0000

47
debian/patches/bugfix/all/ipv4-keep-skb-dst-around-in-presence-of-IP-options.patch vendored Normal file
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@ -0,0 +1,47 @@
From: Eric Dumazet <edumazet@google.com>
Date: Sat, 4 Feb 2017 11:16:52 -0800
Subject: ipv4: keep skb->dst around in presence of IP options
Origin: https://git.kernel.org/linus/34b2cef20f19c87999fff3da4071e66937db9644
Andrey Konovalov got crashes in __ip_options_echo() when a NULL skb->dst
is accessed.
ipv4_pktinfo_prepare() should not drop the dst if (evil) IP options
are present.
We could refine the test to the presence of ts_needtime or srr,
but IP options are not often used, so let's be conservative.
Thanks to syzkaller team for finding this bug.
Fixes: d826eb14ecef ("ipv4: PKTINFO doesnt need dst reference")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/ip_sockglue.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 53ae0c6..9000117 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1238,7 +1238,14 @@ void ipv4_pktinfo_prepare(const struct sock *sk, struct sk_buff *skb)
pktinfo->ipi_ifindex = 0;
pktinfo->ipi_spec_dst.s_addr = 0;
}
- skb_dst_drop(skb);
+ /* We need to keep the dst for __ip_options_echo()
+ * We could restrict the test to opt.ts_needtime || opt.srr,
+ * but the following is good enough as IP options are not often used.
+ */
+ if (unlikely(IPCB(skb)->opt.optlen))
+ skb_dst_force(skb);
+ else
+ skb_dst_drop(skb);
}
int ip_setsockopt(struct sock *sk, int level,
--
2.1.4

1
debian/patches/series vendored
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@ -106,6 +106,7 @@ features/all/securelevel/arm64-add-kernel-config-option-to-set-securelevel-wh.pa
debian/i386-686-pae-pci-set-pci-nobios-by-default.patch
bugfix/all/IB-rxe-Fix-mem_check_range-integer-overflow.patch
bugfix/all/selinux-fix-off-by-one-in-setprocattr.patch
bugfix/all/ipv4-keep-skb-dst-around-in-presence-of-IP-options.patch
# Fix exported symbol versions
bugfix/ia64/revert-ia64-move-exports-to-definitions.patch