[linux] 16/18: net: avoid signed overflows for SO_{SND|RCV}BUFFORCE (CVE-2016-9793)

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benh pushed a commit to branch jessie
in repository linux.

commit 1e8af51ec5566104a10fa393d3f0718f16a77a91
Author: Ben Hutchings <ben at decadent.org.uk>
Date:   Wed Dec 28 23:48:15 2016 +0000

    net: avoid signed overflows for SO_{SND|RCV}BUFFORCE (CVE-2016-9793)
---
 debian/changelog                                   |  1 +
 ...signed-overflows-for-so_-snd-rcv-bufforce.patch | 45 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 3 files changed, 47 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index 53006ac..3a36fac 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -507,6 +507,7 @@ linux (3.16.39-1) UNRELEASED; urgency=medium
   * sg_write()/bsg_write() is not fit to be called under KERNEL_DS
     (CVE-2016-9576)
   * [x86] KVM: drop error recovery in em_jmp_far and em_ret_far (CVE-2016-9756)
+  * net: avoid signed overflows for SO_{SND|RCV}BUFFORCE (CVE-2016-9793)
 
   [ Julien Cristau ]
   * hwrng: Add chaoskey driver, backported from 4.8 (Closes: #839616)
diff --git a/debian/patches/bugfix/all/net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.patch b/debian/patches/bugfix/all/net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.patch
new file mode 100644
index 0000000..d009c20
--- /dev/null
+++ b/debian/patches/bugfix/all/net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.patch
@@ -0,0 +1,45 @@
+From: Eric Dumazet <edumazet at google.com>
+Date: Fri, 2 Dec 2016 09:44:53 -0800
+Subject: net: avoid signed overflows for SO_{SND|RCV}BUFFORCE
+Origin: https://git.kernel.org/linus/b98b0bc8c431e3ceb4b26b0dfc8db509518fb290
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2016-9793
+
+CAP_NET_ADMIN users should not be allowed to set negative
+sk_sndbuf or sk_rcvbuf values, as it can lead to various memory
+corruptions, crashes, OOM...
+
+Note that before commit 82981930125a ("net: cleanups in
+sock_setsockopt()"), the bug was even more serious, since SO_SNDBUF
+and SO_RCVBUF were vulnerable.
+
+This needs to be backported to all known linux kernels.
+
+Again, many thanks to syzkaller team for discovering this gem.
+
+Signed-off-by: Eric Dumazet <edumazet at google.com>
+Reported-by: Andrey Konovalov <andreyknvl at google.com>
+Signed-off-by: David S. Miller <davem at davemloft.net>
+---
+ net/core/sock.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/net/core/sock.c
++++ b/net/core/sock.c
+@@ -741,7 +741,7 @@ int sock_setsockopt(struct socket *sock,
+ 		val = min_t(u32, val, sysctl_wmem_max);
+ set_sndbuf:
+ 		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
+-		sk->sk_sndbuf = max_t(u32, val * 2, SOCK_MIN_SNDBUF);
++		sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);
+ 		/* Wake up sending tasks if we upped the value. */
+ 		sk->sk_write_space(sk);
+ 		break;
+@@ -777,7 +777,7 @@ set_rcvbuf:
+ 		 * returning the value we actually used in getsockopt
+ 		 * is the most desirable behavior.
+ 		 */
+-		sk->sk_rcvbuf = max_t(u32, val * 2, SOCK_MIN_RCVBUF);
++		sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
+ 		break;
+ 
+ 	case SO_RCVBUFFORCE:
diff --git a/debian/patches/series b/debian/patches/series
index 4e08748..521db02 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -674,6 +674,7 @@ bugfix/x86/fix-potential-infoleak-in-older-kernels.patch
 bugfix/all/sctp-validate-chunk-len-before-actually-using-it.patch
 bugfix/all/sg_write-bsg_write-is-not-fit-to-be-called-under-ker.patch
 bugfix/x86/kvm-x86-drop-error-recovery-in-em_jmp_far-and-em_ret.patch
+bugfix/all/net-avoid-signed-overflows-for-so_-snd-rcv-bufforce.patch
 
 # Fix ABI changes
 debian/of-fix-abi-changes.patch

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