syzbot has found a reproducer for 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=1041a3be900000 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) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=160fbd06900000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12a14e6e900000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+3f3837e61a48d32b495f@xxxxxxxxxxxxxxxxxxxxxxxxx ===================================================== BUG: KMSAN: uninit-value in can_receive+0x26b/0x630 net/can/af_can.c:650 CPU: 1 PID: 8475 Comm: syz-executor984 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:ffff8880b8b0f880 EFLAGS: 00000282 RAX: ffff88821fd3bc00 RBX: ffff88812fd1dc00 RCX: 000000021fc9cc00 RDX: ffff88821fc9cc00 RSI: 00000000000004a0 RDI: ffff88812fd1dc00 RBP: ffff8880b8b0f8a8 R08: ffffea000000000f R09: ffff88812fffa000 R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000000 R13: ffff8880b656c2e8 R14: 0000000000000000 R15: 0000000000000282 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_sendmsg+0x6d1/0x840 net/socket.c:2439 __do_sys_sendmsg net/socket.c:2448 [inline] __se_sys_sendmsg+0x97/0xb0 net/socket.c:2446 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2446 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x443559 Code: Bad RIP value. RSP: 002b:00007ffffdad8558 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000443559 RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003 RBP: 00007ffffdad8560 R08: 0000000001bbbbbb R09: 0000000001bbbbbb R10: 0000000001bbbbbb R11: 0000000000000246 R12: 00007ffffdad8570 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 =====================================================
