From b3ae8a62cfdf13821d35467d4150ed983ac556f1 Mon Sep 17 00:00:00 2001
From: Ting-Yu Wang <anivia@google.com>
Date: Wed, 8 Jan 2020 16:29:12 -0800
Subject: Fix slice bounds out of range panic in parsing socket control
 message.

Panic found by syzakller.

PiperOrigin-RevId: 288799046
---
 pkg/sentry/socket/control/control.go     |  6 ++++++
 test/syscalls/linux/socket_ip_unbound.cc | 33 ++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/pkg/sentry/socket/control/control.go b/pkg/sentry/socket/control/control.go
index af1a4e95f..4301b697c 100644
--- a/pkg/sentry/socket/control/control.go
+++ b/pkg/sentry/socket/control/control.go
@@ -471,6 +471,9 @@ func Parse(t *kernel.Task, socketOrEndpoint interface{}, buf []byte) (socket.Con
 		case linux.SOL_IP:
 			switch h.Type {
 			case linux.IP_TOS:
+				if length < linux.SizeOfControlMessageTOS {
+					return socket.ControlMessages{}, syserror.EINVAL
+				}
 				cmsgs.IP.HasTOS = true
 				binary.Unmarshal(buf[i:i+linux.SizeOfControlMessageTOS], usermem.ByteOrder, &cmsgs.IP.TOS)
 				i += AlignUp(length, width)
@@ -481,6 +484,9 @@ func Parse(t *kernel.Task, socketOrEndpoint interface{}, buf []byte) (socket.Con
 		case linux.SOL_IPV6:
 			switch h.Type {
 			case linux.IPV6_TCLASS:
+				if length < linux.SizeOfControlMessageTClass {
+					return socket.ControlMessages{}, syserror.EINVAL
+				}
 				cmsgs.IP.HasTClass = true
 				binary.Unmarshal(buf[i:i+linux.SizeOfControlMessageTClass], usermem.ByteOrder, &cmsgs.IP.TClass)
 				i += AlignUp(length, width)
diff --git a/test/syscalls/linux/socket_ip_unbound.cc b/test/syscalls/linux/socket_ip_unbound.cc
index b6754111f..ca597e267 100644
--- a/test/syscalls/linux/socket_ip_unbound.cc
+++ b/test/syscalls/linux/socket_ip_unbound.cc
@@ -129,6 +129,7 @@ TEST_P(IPUnboundSocketTest, InvalidNegativeTtl) {
 struct TOSOption {
   int level;
   int option;
+  int cmsg_level;
 };
 
 constexpr int INET_ECN_MASK = 3;
@@ -139,10 +140,12 @@ static TOSOption GetTOSOption(int domain) {
     case AF_INET:
       opt.level = IPPROTO_IP;
       opt.option = IP_TOS;
+      opt.cmsg_level = SOL_IP;
       break;
     case AF_INET6:
       opt.level = IPPROTO_IPV6;
       opt.option = IPV6_TCLASS;
+      opt.cmsg_level = SOL_IPV6;
       break;
   }
   return opt;
@@ -386,6 +389,36 @@ TEST_P(IPUnboundSocketTest, NullTOS) {
               SyscallFailsWithErrno(EFAULT));
 }
 
+TEST_P(IPUnboundSocketTest, InsufficientBufferTOS) {
+  SKIP_IF(GetParam().protocol == IPPROTO_TCP);
+
+  auto socket = ASSERT_NO_ERRNO_AND_VALUE(NewSocket());
+  TOSOption t = GetTOSOption(GetParam().domain);
+
+  in_addr addr4;
+  in6_addr addr6;
+  ASSERT_THAT(inet_pton(AF_INET, "127.0.0.1", &addr4), ::testing::Eq(1));
+  ASSERT_THAT(inet_pton(AF_INET6, "fe80::", &addr6), ::testing::Eq(1));
+
+  cmsghdr cmsg = {};
+  cmsg.cmsg_len = sizeof(cmsg);
+  cmsg.cmsg_level = t.cmsg_level;
+  cmsg.cmsg_type = t.option;
+
+  msghdr msg = {};
+  msg.msg_control = &cmsg;
+  msg.msg_controllen = sizeof(cmsg);
+  if (GetParam().domain == AF_INET) {
+    msg.msg_name = &addr4;
+    msg.msg_namelen = sizeof(addr4);
+  } else {
+    msg.msg_name = &addr6;
+    msg.msg_namelen = sizeof(addr6);
+  }
+
+  EXPECT_THAT(sendmsg(socket->get(), &msg, 0), SyscallFailsWithErrno(EINVAL));
+}
+
 INSTANTIATE_TEST_SUITE_P(
     IPUnboundSockets, IPUnboundSocketTest,
     ::testing::ValuesIn(VecCat<SocketKind>(VecCat<SocketKind>(
-- 
cgit v1.2.3