KASAN: use-after-free Read in dev_expire_timer

From: syzbot
Date: Wed Jan 02 2019 - 04:39:07 EST


syzbot found the following crash on:

HEAD commit: 28e8c4bc8eb4 Merge tag 'rtc-4.21' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11eceee7400000
kernel config: https://syzkaller.appspot.com/x/.config?x=c2ab9708c613a224
dashboard link: https://syzkaller.appspot.com/bug?extid=7ea31f54ecacb8f68330
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+7ea31f54ecacb8f68330@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: KASAN: use-after-free in dev_expire_timer+0x414/0x570 drivers/isdn/mISDN/timerdev.c:174
Read of size 8 at addr ffff88809fd76cd0 by task syz-executor1/18425

CPU: 1 PID: 18425 Comm: syz-executor1 Not tainted 4.20.0+ #4
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+0x1db/0x2d0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:135
dev_expire_timer+0x414/0x570 drivers/isdn/mISDN/timerdev.c:174
call_timer_fn+0x254/0x900 kernel/time/timer.c:1325
expire_timers kernel/time/timer.c:1362 [inline]
__run_timers+0x6fc/0xd50 kernel/time/timer.c:1681
run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1694
__do_softirq+0x30b/0xb11 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x180/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1b7/0x760 arch/x86/kernel/apic/apic.c:1062
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
RIP: 0010:memset_erms+0x9/0x10 arch/x86/lib/memset_64.S:66
Code: c1 e9 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 <f3> aa 4c 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01
RSP: 0000:ffff8880531e7118 EFLAGS: 00010206 ORIG_RAX: ffffffffffffff13
RAX: 1ffff11007b40000 RBX: ffffed1007b40000 RCX: 0000000000005e40
RDX: 0000000000040000 RSI: 0000000000000000 RDI: ffffed1007b3a1c0
RBP: ffff8880531e7130 R08: ffff88805a594600 R09: ffffed1007b00000
R10: fffff940001ec006 R11: ffffea0000f60037 R12: 0000000000200000
R13: dffffc0000000000 R14: dffffc0000000000 R15: dffffc0000000000
kasan_alloc_pages+0x38/0x40 mm/kasan/common.c:233
post_alloc_hook mm/page_alloc.c:1949 [inline]
prep_new_page mm/page_alloc.c:1958 [inline]
get_page_from_freelist+0xc7f/0x5190 mm/page_alloc.c:3494
__alloc_pages_nodemask+0x4fd/0xdc0 mm/page_alloc.c:4529
__alloc_pages include/linux/gfp.h:473 [inline]
__alloc_pages_node include/linux/gfp.h:486 [inline]
alloc_pages_vma+0x39a/0x540 mm/mempolicy.c:2062
do_huge_pmd_anonymous_page+0x53a/0x1840 mm/huge_memory.c:738
create_huge_pmd mm/memory.c:3657 [inline]
__handle_mm_fault+0x38e7/0x5690 mm/memory.c:3861
handle_mm_fault+0x4ec/0xc80 mm/memory.c:3927
do_user_addr_fault arch/x86/mm/fault.c:1475 [inline]
__do_page_fault+0x5da/0xd60 arch/x86/mm/fault.c:1541
do_page_fault+0xe6/0x7d8 arch/x86/mm/fault.c:1572
page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
RIP: 0033:0x43f1c1
Code: 8d 15 23 54 0a 00 8b 0c 8a 8b 04 82 29 c8 c3 66 2e 0f 1f 84 00 00 00 00 00 48 83 fa 20 48 89 f8 73 77 f6 c2 01 74 0b 0f b6 0e <88> 0f 48 ff c6 48 ff c7 f6 c2 02 74 12 0f b7 0e 66 89 0f 48 83 c6
RSP: 002b:00007ffcf3a17428 EFLAGS: 00010202
RAX: 0000000020042000 RBX: 0000000000000003 RCX: 000000000000002f
RDX: 000000000000000d RSI: 0000000000740020 RDI: 0000000020042000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000004
R10: 0000000000000075 R11: 0000000000000246 R12: 0000000000000000
R13: fffffffffffffffe R14: 000000000000005c R15: 0000000000000001

Allocated by task 18426:
save_stack+0x45/0xd0 mm/kasan/common.c:73
set_track mm/kasan/common.c:85 [inline]
kasan_kmalloc mm/kasan/common.c:482 [inline]
kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3607
kmalloc include/linux/slab.h:545 [inline]
kzalloc include/linux/slab.h:740 [inline]
misdn_add_timer drivers/isdn/mISDN/timerdev.c:188 [inline]
mISDN_ioctl+0x544/0xc40 drivers/isdn/mISDN/timerdev.c:242
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:509 [inline]
do_vfs_ioctl+0x107b/0x17d0 fs/ioctl.c:696
ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
__do_sys_ioctl fs/ioctl.c:720 [inline]
__se_sys_ioctl fs/ioctl.c:718 [inline]
__x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290

Freed by task 18423:
save_stack+0x45/0xd0 mm/kasan/common.c:73
set_track mm/kasan/common.c:85 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
__cache_free mm/slab.c:3485 [inline]
kfree+0xcf/0x230 mm/slab.c:3804
mISDN_close+0x375/0x530 drivers/isdn/mISDN/timerdev.c:95
__fput+0x3c5/0xb10 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x1f4/0x2b0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293

The buggy address belongs to the object at ffff88809fd76cc0
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 16 bytes inside of
128-byte region [ffff88809fd76cc0, ffff88809fd76d40)
The buggy address belongs to the page:
page:ffffea00027f5d80 count:1 mapcount:0 mapping:ffff88812c3f0640 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000279f148 ffffea00026e6788 ffff88812c3f0640
raw: 0000000000000000 ffff88809fd76000 0000000100000015 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809fd76b80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88809fd76c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809fd76c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88809fd76d00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff88809fd76d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

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