From 4b5fee457723d983868a8cbc140c85bf13845a95 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 12 Aug 2019 04:57:27 -0700 Subject: [PATCH] batman-adv: fix uninit-value in batadv_netlink_get_ifindex() commit 3ee1bb7aae97324ec9078da1f00cb2176919563f upstream. batadv_netlink_get_ifindex() needs to make sure user passed a correct u32 attribute. syzbot reported : BUG: KMSAN: uninit-value in batadv_netlink_dump_hardif+0x70d/0x880 net/batman-adv/netlink.c:968 CPU: 1 PID: 11705 Comm: syz-executor888 Not tainted 5.1.0+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x191/0x1f0 lib/dump_stack.c:113 kmsan_report+0x130/0x2a0 mm/kmsan/kmsan.c:622 __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310 batadv_netlink_dump_hardif+0x70d/0x880 net/batman-adv/netlink.c:968 genl_lock_dumpit+0xc6/0x130 net/netlink/genetlink.c:482 netlink_dump+0xa84/0x1ab0 net/netlink/af_netlink.c:2253 __netlink_dump_start+0xa3a/0xb30 net/netlink/af_netlink.c:2361 genl_family_rcv_msg net/netlink/genetlink.c:550 [inline] genl_rcv_msg+0xfc1/0x1a40 net/netlink/genetlink.c:627 netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2486 genl_rcv+0x63/0x80 net/netlink/genetlink.c:638 netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline] netlink_unicast+0xf3e/0x1020 net/netlink/af_netlink.c:1337 netlink_sendmsg+0x127e/0x12f0 net/netlink/af_netlink.c:1926 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg net/socket.c:661 [inline] ___sys_sendmsg+0xcc6/0x1200 net/socket.c:2260 __sys_sendmsg net/socket.c:2298 [inline] __do_sys_sendmsg net/socket.c:2307 [inline] __se_sys_sendmsg+0x305/0x460 net/socket.c:2305 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2305 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 RIP: 0033:0x440209 Fixes: b60620cf567b ("batman-adv: netlink: hardif query") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: Sven Eckelmann Signed-off-by: Simon Wunderlich Signed-off-by: Greg Kroah-Hartman --- net/batman-adv/netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c index 0d9459b..c328209 100644 --- a/net/batman-adv/netlink.c +++ b/net/batman-adv/netlink.c @@ -118,7 +118,7 @@ batadv_netlink_get_ifindex(const struct nlmsghdr *nlh, int attrtype) { struct nlattr *attr = nlmsg_find_attr(nlh, GENL_HDRLEN, attrtype); - return attr ? nla_get_u32(attr) : 0; + return (attr && nla_len(attr) == sizeof(u32)) ? nla_get_u32(attr) : 0; } /** -- 2.7.4