Subject: KMSAN: uninit-value in can_receive (2)

From: syzbot <[email-masked]>
Date: Sun, 09 Aug 2020 09:27:17 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    ce8056d1 wip: changed copy_from_user where instrumented
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1195d1aa900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3afe005fb99591f
dashboard link: https://syzkaller.appspot.com/bug?extid=3f3837e61a48d32b495f
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386

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

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

=====================================================
BUG: KMSAN: uninit-value in can_receive+0x26b/0x630 net/can/af_can.c:650
CPU: 1 PID: 15859 Comm: syz-executor.2 Not tainted 5.8.0-rc5-syzkaller #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+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 can_receive+0x26b/0x630 net/can/af_can.c:650
 can_rcv+0x1fb/0x410 net/can/af_can.c:686
 __netif_receive_skb_one_core net/core/dev.c:5281 [inline]
 __netif_receive_skb+0x265/0x670 net/core/dev.c:5395
 process_backlog+0x50d/0xba0 net/core/dev.c:6239
 napi_poll+0x43b/0xfd0 net/core/dev.c:6684
 net_rx_action+0x35c/0xd40 net/core/dev.c:6752
 __do_softirq+0x2ea/0x7f5 kernel/softirq.c:293
 asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:711
 </IRQ>
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:23 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:50 [inline]
 do_softirq_own_stack+0x7c/0xa0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:390 [inline]
 __irq_exit_rcu+0x226/0x270 kernel/softirq.c:420
 irq_exit_rcu+0xe/0x10 kernel/softirq.c:432
 sysvec_apic_timer_interrupt+0x107/0x130 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:593
RIP: 0010:_raw_spin_unlock_irqrestore+0x4b/0x70 kernel/locking/spinlock.c:192
Code: 00 8b b8 88 0c 00 00 48 8b 00 48 85 c0 75 28 48 89 df e8 b8 6e 4b f1 c6 00 00 c6 03 00 4d 85 e4 75 1c 4c 89 7d d8 ff 75 d8 9d <48> 83 c4 08 5b 41 5c 41 5e 41 5f 5d c3 e8 53 74 4b f1 eb d1 44 89
RSP: 0018:ffff8880204ff720 EFLAGS: 00000286
RAX: ffff88821fd3bc00 RBX: ffff88812fd1dc00 RCX: 000000021fc9cc00
RDX: ffff88821fc9cc00 RSI: 00000000000004a0 RDI: ffff88812fd1dc00
RBP: ffff8880204ff748 R08: ffffea000000000f R09: ffff88812fffa000
R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88812dfff4e8 R14: 0000000000000000 R15: 0000000000000286
 unlock_hrtimer_base kernel/time/hrtimer.c:898 [inline]
 hrtimer_start_range_ns+0x459/0x4e0 kernel/time/hrtimer.c:1136
 hrtimer_start include/linux/hrtimer.h:421 [inline]
 j1939_tp_schedule_txtimer+0x132/0x1b0 net/can/j1939/transport.c:671
 j1939_sk_send_loop net/can/j1939/socket.c:1047 [inline]
 j1939_sk_sendmsg+0x1cc0/0x2950 net/can/j1939/socket.c:1160
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 ____sys_sendmsg+0xc82/0x1240 net/socket.c:2352
 ___sys_sendmsg net/socket.c:2406 [inline]
 __sys_sendmmsg+0x808/0xf70 net/socket.c:2489
 __compat_sys_sendmmsg net/compat.c:480 [inline]
 __do_compat_sys_sendmmsg net/compat.c:487 [inline]
 __se_compat_sys_sendmmsg+0xcd/0xf0 net/compat.c:484
 __ia32_compat_sys_sendmmsg+0x56/0x70 net/compat.c:484
 do_syscall_32_irqs_on arch/x86/entry/common.c:430 [inline]
 __do_fast_syscall_32+0x2af/0x480 arch/x86/entry/common.c:477
 do_fast_syscall_32+0x6b/0xd0 arch/x86/entry/common.c:505
 do_SYSENTER_32+0x73/0x90 arch/x86/entry/common.c:554
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf7fad549
Code: Bad RIP value.
RSP: 002b:00000000f55a70cc EFLAGS: 00000296 ORIG_RAX: 0000000000000159
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200000c0
RDX: 00000000924924d8 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:80
 slab_alloc_node mm/slub.c:2839 [inline]
 __kmalloc_node_track_caller+0xeab/0x12e0 mm/slub.c:4478
 __kmalloc_reserve net/core/skbuff.c:142 [inline]
 __alloc_skb+0x35f/0xb30 net/core/skbuff.c:210
 alloc_skb include/linux/skbuff.h:1083 [inline]
 j1939_tp_tx_dat_new net/can/j1939/transport.c:568 [inline]
 j1939_xtp_do_tx_ctl net/can/j1939/transport.c:628 [inline]
 j1939_tp_tx_ctl net/can/j1939/transport.c:646 [inline]
 j1939_session_tx_rts net/can/j1939/transport.c:714 [inline]
 j1939_xtp_txnext_transmiter net/can/j1939/transport.c:832 [inline]
 j1939_tp_txtimer+0x402c/0x6980 net/can/j1939/transport.c:1095
 __run_hrtimer+0x7cd/0xf00 kernel/time/hrtimer.c:1520
 __hrtimer_run_queues kernel/time/hrtimer.c:1584 [inline]
 hrtimer_run_softirq+0x3bf/0x690 kernel/time/hrtimer.c:1601
 __do_softirq+0x2ea/0x7f5 kernel/softirq.c:293
=====================================================

---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at [email-masked].

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.