KASAN: use-after-free Write in __internal_add_timer

[syzbot]

Hello,

syzkaller hit the following crash on
9c323bff13f92832e03657cabdd70d731408d621
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers
CC: [john....@linaro.org linux-...@vger.kernel.org
sb...@codeaurora.org tg...@linutronix.de]

BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:673
[inline]
BUG: KASAN: use-after-free in enqueue_timer kernel/time/timer.c:520 [inline]
BUG: KASAN: use-after-free in __internal_add_timer+0x275/0x2d0
kernel/time/timer.c:531
Write of size 8 at addr ffff8801d1eb3600 by task syzkaller453449/2985

CPU: 1 PID: 2985 Comm: syzkaller453449 Not tainted 4.14.0-rc5+ #51
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:52
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_error mm/kasan/report.c:351 [inline]
kasan_report+0x25b/0x340 mm/kasan/report.c:409
__asan_report_store8_noabort+0x17/0x20 mm/kasan/report.c:435
hlist_add_head include/linux/list.h:673 [inline]
enqueue_timer kernel/time/timer.c:520 [inline]
__internal_add_timer+0x275/0x2d0 kernel/time/timer.c:531
internal_add_timer kernel/time/timer.c:573 [inline]
__mod_timer kernel/time/timer.c:1024 [inline]
mod_timer+0x622/0x15b0 kernel/time/timer.c:1071
tun_flow_init drivers/net/tun.c:1098 [inline]
tun_set_iff drivers/net/tun.c:2060 [inline]
__tun_chr_ioctl+0x1b17/0x3d20 drivers/net/tun.c:2278
tun_chr_compat_ioctl+0x29/0x30 drivers/net/tun.c:2551
C_SYSC_ioctl fs/compat_ioctl.c:1593 [inline]
compat_SyS_ioctl+0x1d7/0x3290 fs/compat_ioctl.c:1540
do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391
entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124
RIP: 0023:0xf7f2ac79
RSP: 002b:00000000ff96d4dc EFLAGS: 00000286 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00000000400454ca
RDX: 0000000020fbcfd8 RSI: 00000000080ef00c RDI: 000000000000003f
RBP: 0000000000001000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 2985:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
__do_kmalloc_node mm/slab.c:3689 [inline]
__kmalloc_node+0x47/0x70 mm/slab.c:3696
kmalloc_node include/linux/slab.h:535 [inline]
kvmalloc_node+0x64/0xd0 mm/util.c:397
kvmalloc include/linux/mm.h:529 [inline]
kvzalloc include/linux/mm.h:537 [inline]
alloc_netdev_mqs+0x16e/0xed0 net/core/dev.c:8023
tun_set_iff drivers/net/tun.c:2024 [inline]
__tun_chr_ioctl+0x12b2/0x3d20 drivers/net/tun.c:2278
tun_chr_compat_ioctl+0x29/0x30 drivers/net/tun.c:2551
C_SYSC_ioctl fs/compat_ioctl.c:1593 [inline]
compat_SyS_ioctl+0x1d7/0x3290 fs/compat_ioctl.c:1540
do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391
entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124

Freed by task 2985:
save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3503 [inline]
kfree+0xca/0x250 mm/slab.c:3820
kvfree+0x36/0x60 mm/util.c:416
netdev_freemem net/core/dev.c:7975 [inline]
free_netdev+0x2cf/0x360 net/core/dev.c:8137
tun_set_iff drivers/net/tun.c:2107 [inline]
__tun_chr_ioctl+0x2cea/0x3d20 drivers/net/tun.c:2278
tun_chr_compat_ioctl+0x29/0x30 drivers/net/tun.c:2551
C_SYSC_ioctl fs/compat_ioctl.c:1593 [inline]
compat_SyS_ioctl+0x1d7/0x3290 fs/compat_ioctl.c:1540
do_syscall_32_irqs_on arch/x86/entry/common.c:329 [inline]
do_fast_syscall_32+0x3f2/0xf05 arch/x86/entry/common.c:391
entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124

The buggy address belongs to the object at ffff8801d1eb02c0
which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 13120 bytes inside of
16384-byte region [ffff8801d1eb02c0, ffff8801d1eb42c0)
The buggy address belongs to the page:
page:ffffea000747ac00 count:1 mapcount:0 mapping:ffff8801d1eb02c0 index:0x0
compound_mapcount: 0
flags: 0x200000000008100(slab|head)
raw: 0200000000008100 ffff8801d1eb02c0 0000000000000000 0000000100000001
raw: ffffea0007667820 ffffea000748e620 ffff8801dac02200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d1eb3500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d1eb3580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801d1eb3600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8801d1eb3680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801d1eb3700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzk...@googlegroups.com.
Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>

syzbot will keep track of this bug report.
Once a fix for this bug is committed, please reply to this email with:
#syz fix: exact-commit-title
To mark this as a duplicate of another syzbot report, please reply with:
#syz dup: exact-subject-of-another-report
If it's a one-off invalid bug report, please reply with:
#syz invalid
Note: if the crash happens again, it will cause creation of a new bug
report.
Note: all commands must start from beginning of the line.
To upstream this report, please reply with:
#syz upstream

[Dmitry Vyukov]

last happened 2 week ago, repros don't work anymore, there were a
recent fix for tun timers

#syz invalid


On Wed, Nov 1, 2017 at 9:14 PM, syzbot
<bot+e99ef70b1aab1991b9...@syzkaller.appspotmail.com>
wrote:

> --
> You received this message because you are subscribed to the Google Groups
> "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to syzkaller-upstream-m...@googlegroups.com.
> To post to this group, send email to
> syzkaller-upst...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/syzkaller-upstream-moderation/001a11404e227d7e75055cefd733%40google.com.
> For more options, visit https://groups.google.com/d/optout.