linux-kernel - Use-after-scope Read in tick_sched

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Date:   Wed, 02 May 2018 11:07:17 +0000
From:   Dongsong Yu <yudongsong1992@...il.com>
To:     linux-kernel@...r.kernel.org
Subject: Use-after-scope Read in tick_sched_handle' bug.(Plain text)

Hi,
I've got the following bug report while fuzzing linux kenrel (4.16.0) on
arm64 with syzkaller.
The kernel config file and poc generated by C reproducer are attached.

Syzkaller hit 'KASAN: use-after-scope Read in tick_sched_handle' bug.


==================================================================
BUG: KASAN: use-after-scope in tick_sched_handle.isra.5+0x64/0xa8
kernel/time/tick-sched.c:162
Read of size 8 at addr ffff800073866578 by task syzkaller195252/1474

CPU: 0 PID: 1474 Comm: syzkaller195252 Not tainted 4.16.0 #2
Hardware name: linux,dummy-virt (DT)
Call trace:
  dump_backtrace+0x0/0x350 arch/arm64/kernel/time.c:64
  show_stack+0x20/0x30 arch/arm64/kernel/traps.c:151
  __dump_stack lib/dump_stack.c:17 [inline]
  dump_stack+0x11c/0x198 lib/dump_stack.c:53
  print_address_description+0x60/0x270 mm/kasan/report.c:256
  kasan_report_error mm/kasan/report.c:354 [inline]
  kasan_report+0x248/0x348 mm/kasan/report.c:412
  check_memory_region_inline mm/kasan/kasan.c:260 [inline]
  __asan_load8+0x84/0xa8 mm/kasan/kasan.c:698
  tick_sched_handle.isra.5+0x64/0xa8 kernel/time/tick-sched.c:162
  tick_sched_timer+0x50/0xe0 kernel/time/tick-sched.c:1194
  __run_hrtimer kernel/time/hrtimer.c:1349 [inline]
  __hrtimer_run_queues+0x1dc/0x2c0 kernel/time/hrtimer.c:1411
  hrtimer_interrupt+0x180/0x390 kernel/time/hrtimer.c:1469
  timer_handler drivers/clocksource/arm_arch_timer.c:588 [inline]
  arch_timer_handler_virt+0x44/0x70 drivers/clocksource/arm_arch_timer.c:599
  handle_percpu_devid_irq+0xdc/0x1e8 kernel/irq/chip.c:896
  generic_handle_irq_desc include/linux/irqdesc.h:159 [inline]
  generic_handle_irq+0x48/0x68 kernel/irq/irqdesc.c:606
  __handle_domain_irq+0x8c/0x108 kernel/irq/irqdesc.c:643
  handle_domain_irq include/linux/irqdesc.h:177 [inline]
  gic_handle_irq+0x6c/0xd8 drivers/irqchip/irq-gic.c:367
  el1_irq+0xb0/0x128 arch/arm64/kernel/entry.S:602
  prep_new_page mm/page_alloc.c:1816 [inline]
  get_page_from_freelist+0x628/0x1998 mm/page_alloc.c:3239
  __alloc_pages_nodemask+0x244/0x1600 mm/page_alloc.c:4245
  alloc_pages_current+0x128/0x1f0 mm/mempolicy.c:2055
  alloc_pages include/linux/gfp.h:492 [inline]
  pte_alloc_one arch/arm64/include/asm/pgalloc.h:104 [inline]
  __pte_alloc+0x8c/0x200 mm/memory.c:654
  do_anonymous_page+0x844/0x9b0 mm/memory.c:3141
  handle_pte_fault mm/memory.c:3977 [inline]
  __handle_mm_fault+0xb94/0x1528 mm/memory.c:4103
  handle_mm_fault+0x288/0x3e0 mm/memory.c:4140
  __do_page_fault arch/arm64/mm/fault.c:377 [inline]
  do_page_fault+0x398/0x630 arch/arm64/mm/fault.c:459
  do_translation_fault+0x90/0xb0 arch/arm64/mm/fault.c:561
  do_mem_abort+0xbc/0x208 arch/arm64/mm/fault.c:698
  el0_da+0x20/0x24

The buggy address belongs to the page:
page:ffff7e0001ce1980 count:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x4fffc00000000000()
raw: 4fffc00000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffff7e0001ce19a0 ffff7e0001ce19a0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff800073866400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  ffff800073866480: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
> ffff800073866500: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                                                                 ^
  ffff800073866580: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
  ffff800073866600: f8 f8 f8 f8 f8 f8 00 00 00 00 00 00 00 00 00 00
==================================================================

View attachment "report-tick_sched_handle.txt" of type "text/plain" (96779 bytes)

Download attachment "config" of type "application/octet-stream" (165109 bytes)

Download attachment "tick_sched_handle.c" of type "application/octet-stream" (3223 bytes)