From: Dave Watson <davejwatson@fb.com>
Date: Mon, 26 Jun 2017 08:36:47 -0700
Subject: tcp: fix null ptr deref in getsockopt(..., TCP_ULP, ...)
Git-commit: d97af30f615eea23ecfefd0e80b2f5f2f41afe55
Patch-mainline: v4.13-rc1
References: bnc#1129168
If icsk_ulp_ops is unset, it dereferences a null ptr.
Add a null ptr check.
BUG: KASAN: null-ptr-deref in copy_to_user include/linux/uaccess.h:168 [inline]
BUG: KASAN: null-ptr-deref in do_tcp_getsockopt.isra.33+0x24f/0x1e30 net/ipv4/tcp.c:3057
Read of size 4 at addr 0000000000000020 by task syz-executor1/15452
Signed-off-by: Dave Watson <davejwatson@fb.com>
Reported-by: "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/ipv4/tcp.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3043,6 +3043,11 @@ static int do_tcp_getsockopt(struct sock
if (get_user(len, optlen))
return -EFAULT;
len = min_t(unsigned int, len, TCP_ULP_NAME_MAX);
+ if (!icsk->icsk_ulp_ops) {
+ if (put_user(0, optlen))
+ return -EFAULT;
+ return 0;
+ }
if (put_user(len, optlen))
return -EFAULT;
if (copy_to_user(optval, icsk->icsk_ulp_ops->name, len))