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Date:   Mon, 18 Nov 2019 11:05:09 -0800
Message-ID: <0000000000005c08d10597a3a05d@google.com>
Subject: KMSAN: uninit-value in can_receive
From:   syzbot <syzbot+b02ff0707a97e4e79ebb@syzkaller.appspotmail.com>
To:     davem@davemloft.net, glider@google.com, linux-can@vger.kernel.org,
        linux-kernel@vger.kernel.org, mkl@pengutronix.de,
        netdev@vger.kernel.org, socketcan@hartkopp.net,
        syzkaller-bugs@googlegroups.com
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Sender: linux-kernel-owner@vger.kernel.org
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Hello,

syzbot found the following crash on:

HEAD commit:    9c6a7162 kmsan: remove unneeded annotations in bio
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=14563416e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9e324dfe9c7b0360
dashboard link: https://syzkaller.appspot.com/bug?extid=b02ff0707a97e4e79ebb
compiler:       clang version 9.0.0 (/home/glider/llvm/clang  
80fee25776c2fb61e74c1ecb1a523375c2500b69)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+b02ff0707a97e4e79ebb@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in can_receive+0x23c/0x5e0 net/can/af_can.c:649
CPU: 1 PID: 3490 Comm: syz-executor.2 Not tainted 5.4.0-rc5+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  <IRQ>
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x191/0x1f0 lib/dump_stack.c:113
  kmsan_report+0x128/0x220 mm/kmsan/kmsan_report.c:108
  __msan_warning+0x73/0xe0 mm/kmsan/kmsan_instr.c:245
  can_receive+0x23c/0x5e0 net/can/af_can.c:649
  can_rcv+0x188/0x3a0 net/can/af_can.c:685
  __netif_receive_skb_one_core net/core/dev.c:5010 [inline]
  __netif_receive_skb net/core/dev.c:5124 [inline]
  process_backlog+0x12e8/0x1410 net/core/dev.c:5955
  napi_poll net/core/dev.c:6392 [inline]
  net_rx_action+0x7a6/0x1aa0 net/core/dev.c:6460
  __do_softirq+0x4a1/0x83a kernel/softirq.c:293
  do_softirq_own_stack+0x49/0x80 arch/x86/entry/entry_64.S:1093
  </IRQ>
  do_softirq kernel/softirq.c:338 [inline]
  __local_bh_enable_ip+0x184/0x1d0 kernel/softirq.c:190
  local_bh_enable+0x36/0x40 include/linux/bottom_half.h:32
  rcu_read_unlock_bh include/linux/rcupdate.h:688 [inline]
  __dev_queue_xmit+0x38e8/0x4200 net/core/dev.c:3900
  dev_queue_xmit+0x4b/0x60 net/core/dev.c:3906
  packet_snd net/packet/af_packet.c:2959 [inline]
  packet_sendmsg+0x82d7/0x92e0 net/packet/af_packet.c:2984
  sock_sendmsg_nosec net/socket.c:637 [inline]
  sock_sendmsg net/socket.c:657 [inline]
  ___sys_sendmsg+0x14ff/0x1590 net/socket.c:2311
  __sys_sendmsg net/socket.c:2356 [inline]
  __do_sys_sendmsg net/socket.c:2365 [inline]
  __se_sys_sendmsg+0x305/0x460 net/socket.c:2363
  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2363
  do_syscall_64+0xb6/0x160 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x45a639
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ff1b9c14c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a639
RDX: 0000000000000050 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff1b9c156d4
R13: 00000000004c8acf R14: 00000000004df078 R15: 00000000ffffffff

Uninit was created at:
  kmsan_save_stack_with_flags mm/kmsan/kmsan.c:151 [inline]
  kmsan_internal_poison_shadow+0x60/0x120 mm/kmsan/kmsan.c:134
  kmsan_slab_alloc+0xaa/0x120 mm/kmsan/kmsan_hooks.c:88
  slab_alloc_node mm/slub.c:2799 [inline]
  __kmalloc_node_track_caller+0xd7b/0x1390 mm/slub.c:4407
  __kmalloc_reserve net/core/skbuff.c:141 [inline]
  __alloc_skb+0x306/0xa10 net/core/skbuff.c:209
  alloc_skb include/linux/skbuff.h:1050 [inline]
  alloc_skb_with_frags+0x18c/0xa80 net/core/skbuff.c:5662
  sock_alloc_send_pskb+0xafd/0x10a0 net/core/sock.c:2244
  packet_alloc_skb net/packet/af_packet.c:2807 [inline]
  packet_snd net/packet/af_packet.c:2902 [inline]
  packet_sendmsg+0x6785/0x92e0 net/packet/af_packet.c:2984
  sock_sendmsg_nosec net/socket.c:637 [inline]
  sock_sendmsg net/socket.c:657 [inline]
  ___sys_sendmsg+0x14ff/0x1590 net/socket.c:2311
  __sys_sendmsg net/socket.c:2356 [inline]
  __do_sys_sendmsg net/socket.c:2365 [inline]
  __se_sys_sendmsg+0x305/0x460 net/socket.c:2363
  __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2363
  do_syscall_64+0xb6/0x160 arch/x86/entry/common.c:291
  entry_SYSCALL_64_after_hwframe+0x63/0xe7
=====================================================


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