Subject: KMSAN: uninit-value in xfrm_state_find

From: syzbot <[email-masked]>
Date: Fri, 15 Jun 2018 00:30:02 -0700

Hello,

syzbot found the following crash on:

HEAD commit:    1df165c8d2d6 kmsan: introduce kmsan_clear_user_page()
git tree:       https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=15336e97800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4ca1e57bafa8ab1f
dashboard link: https://syzkaller.appspot.com/bug?extid=131cd4c6d21724b99a26
compiler:       clang version 7.0.0 (trunk 329391)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=12c7a417800000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13710197800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email-masked]

IPv6: ADDRCONF(NETDEV_UP): veth1: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
==================================================================
BUG: KMSAN: uninit-value in __arch_swab32  
arch/x86/include/uapi/asm/swab.h:10 [inline]
BUG: KMSAN: uninit-value in __fswab32 include/uapi/linux/swab.h:59 [inline]
BUG: KMSAN: uninit-value in __xfrm6_daddr_saddr_hash  
net/xfrm/xfrm_hash.h:29 [inline]
BUG: KMSAN: uninit-value in __xfrm_dst_hash net/xfrm/xfrm_hash.h:96 [inline]
BUG: KMSAN: uninit-value in xfrm_dst_hash net/xfrm/xfrm_state.c:60 [inline]
BUG: KMSAN: uninit-value in xfrm_state_find+0x2b15/0x4f40  
net/xfrm/xfrm_state.c:952
CPU: 0 PID: 4464 Comm: syz-executor988 Not tainted 4.17.0-rc3+ #93
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+0x185/0x1d0 lib/dump_stack.c:113
  kmsan_report+0x142/0x240 mm/kmsan/kmsan.c:1084
  __msan_warning_32+0x6c/0xb0 mm/kmsan/kmsan_instr.c:683
  __arch_swab32 arch/x86/include/uapi/asm/swab.h:10 [inline]
  __fswab32 include/uapi/linux/swab.h:59 [inline]
  __xfrm6_daddr_saddr_hash net/xfrm/xfrm_hash.h:29 [inline]
  __xfrm_dst_hash net/xfrm/xfrm_hash.h:96 [inline]
  xfrm_dst_hash net/xfrm/xfrm_state.c:60 [inline]
  xfrm_state_find+0x2b15/0x4f40 net/xfrm/xfrm_state.c:952
  xfrm_tmpl_resolve_one net/xfrm/xfrm_policy.c:1393 [inline]
  xfrm_tmpl_resolve net/xfrm/xfrm_policy.c:1437 [inline]
  xfrm_resolve_and_create_bundle+0xc31/0x5270 net/xfrm/xfrm_policy.c:1833
  xfrm_lookup+0x606/0x39d0 net/xfrm/xfrm_policy.c:2163
  xfrm_lookup_route+0xfa/0x360 net/xfrm/xfrm_policy.c:2283
  ip_route_output_flow+0x35b/0x3b0 net/ipv4/route.c:2574
  udp_sendmsg+0x2289/0x33f0 net/ipv4/udp.c:1006
  udpv6_sendmsg+0x1291/0x3f40 net/ipv6/udp.c:1175
  inet_sendmsg+0x48d/0x740 net/ipv4/af_inet.c:798
  sock_sendmsg_nosec net/socket.c:629 [inline]
  sock_sendmsg net/socket.c:639 [inline]
  ___sys_sendmsg+0xec0/0x1310 net/socket.c:2117
  __sys_sendmmsg+0x490/0x850 net/socket.c:2212
  __do_sys_sendmmsg net/socket.c:2241 [inline]
  __se_sys_sendmmsg net/socket.c:2238 [inline]
  __x64_sys_sendmmsg+0x11c/0x170 net/socket.c:2238
  do_syscall_64+0x154/0x220 arch/x86/entry/common.c:287
  entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4419c9
RSP: 002b:00007ffdb3fa4608 EFLAGS: 00000217 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004419c9
RDX: 0000000000000001 RSI: 0000000020002000 RDI: 0000000000000003
RBP: 00000000006cd018 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000217 R12: 00000000004026c0
R13: 0000000000402750 R14: 0000000000000000 R15: 0000000000000000

Local variable description: ----fl4_stack@udp_sendmsg
Variable was created at:
  udp_sendmsg+0xe5/0x33f0 net/ipv4/udp.c:841
  udpv6_sendmsg+0x1291/0x3f40 net/ipv6/udp.c:1175
==================================================================

---
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