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SubjectKASAN: use-after-free Read in __hrtimer_run_queues

syzbot found the following crash on:

HEAD commit: 673b41e0 staging/octeon: fix up merge error
git tree: upstream
console output:
kernel config:
dashboard link:
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
syz repro:
C reproducer:

The bug was bisected to:

commit 40db173965c05a1d803451240ed41707d5bd978d
Author: Sebastian Andrzej Siewior <>
Date: Sat Mar 21 11:26:02 2020 +0000

lockdep: Add hrtimer context tracing bits

bisection log:
final crash:
console output:

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Fixes: 40db173965c0 ("lockdep: Add hrtimer context tracing bits")

vxcan0: j1939_tp_rxtimer: 0x00000000008c9d66: rx timeout, send abort
vxcan0: j1939_tp_rxtimer: 0x00000000008c9d66: abort rx timeout. Force session deactivation
BUG: KASAN: use-after-free in __run_hrtimer kernel/time/hrtimer.c:1521 [inline]
BUG: KASAN: use-after-free in __hrtimer_run_queues+0xe18/0xf10 kernel/time/hrtimer.c:1583
Read of size 1 at addr ffff8880934d1d73 by task swapper/1/0

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd3/0x315 mm/kasan/report.c:374
__kasan_report.cold+0x1a/0x32 mm/kasan/report.c:506
kasan_report+0xe/0x20 mm/kasan/common.c:641
__run_hrtimer kernel/time/hrtimer.c:1521 [inline]
__hrtimer_run_queues+0xe18/0xf10 kernel/time/hrtimer.c:1583
hrtimer_run_softirq+0x16d/0x250 kernel/time/hrtimer.c:1600
__do_softirq+0x26c/0x9f7 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x192/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x19e/0x600 arch/x86/kernel/apic/apic.c:1140
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: cc cc cc cc cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 94 59 4c 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 84 59 4c 00 fb f4 <c3> cc 41 56 41 55 41 54 55 53 e8 63 8d a4 f9 e8 9e 9f d7 fb 0f 1f
RSP: 0018:ffffc90000d3fdb8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff12e90e7 RBX: ffff8880a9638340 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a9638bfc
RBP: dffffc0000000000 R08: ffff8880a9638340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffed10152c7068
R13: 0000000000000001 R14: ffffffff8a673000 R15: 0000000000000000
arch_safe_halt arch/x86/include/asm/paravirt.h:144 [inline]
default_idle+0x49/0x350 arch/x86/kernel/process.c:695
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x393/0x690 kernel/sched/idle.c:269
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:361
start_secondary+0x2f3/0x400 arch/x86/kernel/smpboot.c:268
secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242

Allocated by task 7030:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
__kasan_kmalloc mm/kasan/common.c:515 [inline]
__kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:488
kmem_cache_alloc_trace+0x153/0x7d0 mm/slab.c:3551
kmalloc include/linux/slab.h:555 [inline]
kzalloc include/linux/slab.h:669 [inline]
j1939_session_new+0x7c/0x3f0 net/can/j1939/transport.c:1418
j1939_tp_send+0x22f/0x800 net/can/j1939/transport.c:1877
j1939_sk_send_loop net/can/j1939/socket.c:1037 [inline]
j1939_sk_sendmsg+0xabf/0x1360 net/can/j1939/socket.c:1160
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x6bf/0x7e0 net/socket.c:2362
___sys_sendmsg+0x100/0x170 net/socket.c:2416
__sys_sendmsg+0xec/0x1b0 net/socket.c:2449
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139

Freed by task 0:
save_stack+0x1b/0x80 mm/kasan/common.c:72
set_track mm/kasan/common.c:80 [inline]
kasan_set_free_info mm/kasan/common.c:337 [inline]
__kasan_slab_free+0xf7/0x140 mm/kasan/common.c:476
__cache_free mm/slab.c:3426 [inline]
kfree+0x109/0x2b0 mm/slab.c:3757
j1939_session_destroy net/can/j1939/transport.c:276 [inline]
__j1939_session_release net/can/j1939/transport.c:284 [inline]
kref_put include/linux/kref.h:65 [inline]
j1939_session_put+0x25c/0x330 net/can/j1939/transport.c:289
j1939_tp_rxtimer+0x2e9/0x2f4 net/can/j1939/transport.c:1194
__run_hrtimer kernel/time/hrtimer.c:1519 [inline]
__hrtimer_run_queues+0x3a2/0xf10 kernel/time/hrtimer.c:1583
hrtimer_run_softirq+0x16d/0x250 kernel/time/hrtimer.c:1600
__do_softirq+0x26c/0x9f7 kernel/softirq.c:292

The buggy address belongs to the object at ffff8880934d1c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 371 bytes inside of
512-byte region [ffff8880934d1c00, ffff8880934d1e00)
The buggy address belongs to the page:
page:ffffea00024d3440 refcount:1 mapcount:0 mapping:ffff8880aa000a80 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00024fbd48 ffffea00024fb888 ffff8880aa000a80
raw: 0000000000000000 ffff8880934d1000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880934d1c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880934d1c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880934d1d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880934d1d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880934d1e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

This bug is generated by a bot. It may contain errors.
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For information about bisection process see:
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