batman-adv/patches/0033-batman-adv-fix-uninit-value-in-batadv_netlink_get_if.patch

   1 From: Eric Dumazet <edumazet@google.com>
   2 Date: Mon, 12 Aug 2019 04:57:27 -0700
   3 Subject: batman-adv: fix uninit-value in batadv_netlink_get_ifindex()
   4
   5 batadv_netlink_get_ifindex() needs to make sure user passed
   6 a correct u32 attribute.
   7
   8 syzbot reported :
   9 BUG: KMSAN: uninit-value in batadv_netlink_dump_hardif+0x70d/0x880 net/batman-adv/netlink.c:968
  10 CPU: 1 PID: 11705 Comm: syz-executor888 Not tainted 5.1.0+ #1
  11 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  12 Call Trace:
  13  __dump_stack lib/dump_stack.c:77 [inline]
  14  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
  15  kmsan_report+0x130/0x2a0 mm/kmsan/kmsan.c:622
  16  __msan_warning+0x75/0xe0 mm/kmsan/kmsan_instr.c:310
  17  batadv_netlink_dump_hardif+0x70d/0x880 net/batman-adv/netlink.c:968
  18  genl_lock_dumpit+0xc6/0x130 net/netlink/genetlink.c:482
  19  netlink_dump+0xa84/0x1ab0 net/netlink/af_netlink.c:2253
  20  __netlink_dump_start+0xa3a/0xb30 net/netlink/af_netlink.c:2361
  21  genl_family_rcv_msg net/netlink/genetlink.c:550 [inline]
  22  genl_rcv_msg+0xfc1/0x1a40 net/netlink/genetlink.c:627
  23  netlink_rcv_skb+0x431/0x620 net/netlink/af_netlink.c:2486
  24  genl_rcv+0x63/0x80 net/netlink/genetlink.c:638
  25  netlink_unicast_kernel net/netlink/af_netlink.c:1311 [inline]
  26  netlink_unicast+0xf3e/0x1020 net/netlink/af_netlink.c:1337
  27  netlink_sendmsg+0x127e/0x12f0 net/netlink/af_netlink.c:1926
  28  sock_sendmsg_nosec net/socket.c:651 [inline]
  29  sock_sendmsg net/socket.c:661 [inline]
  30  ___sys_sendmsg+0xcc6/0x1200 net/socket.c:2260
  31  __sys_sendmsg net/socket.c:2298 [inline]
  32  __do_sys_sendmsg net/socket.c:2307 [inline]
  33  __se_sys_sendmsg+0x305/0x460 net/socket.c:2305
  34  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2305
  35  do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
  36  entry_SYSCALL_64_after_hwframe+0x63/0xe7
  37 RIP: 0033:0x440209
  38
  39 Fixes: 55d368c3a57e ("batman-adv: netlink: hardif query")
  40 Signed-off-by: Eric Dumazet <edumazet@google.com>
  41 Reported-by: syzbot <syzkaller@googlegroups.com>
  42 Signed-off-by: Sven Eckelmann <sven@narfation.org>
  43
  44 Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/9b470b8a2b9ef4ce68d6e95febd3a0574be1ac14
  45
  46 diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
  47 index 0d9459b69bdb812b1b68e28e6b68fec8ec95df2d..c32820963b8e706b4cdde10d46ec582bc51ec4eb 100644
  48 --- a/net/batman-adv/netlink.c
  49 +++ b/net/batman-adv/netlink.c
  50 @@ -118,7 +118,7 @@ batadv_netlink_get_ifindex(const struct nlmsghdr *nlh, int attrtype)
  51  {
  52         struct nlattr *attr = nlmsg_find_attr(nlh, GENL_HDRLEN, attrtype);
  53
  54 -       return attr ? nla_get_u32(attr) : 0;
  55 +       return (attr && nla_len(attr) == sizeof(u32)) ? nla_get_u32(attr) : 0;
  56  }
  57
  58  /**