Messages in this thread | | | Date | Wed, 15 Nov 2017 13:31:37 +0000 (UTC) | From | Mathieu Desnoyers <> | Subject | Re: KASAN: use-after-free in membarrier_mm_sync_core_before_usermode |
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----- On Nov 15, 2017, at 8:05 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
> ----- On Nov 15, 2017, at 5:44 AM, Dmitry Vyukov dvyukov@google.com wrote: > >> Hello, >> >> I've tried to run latest linux-next on: >> >> commit 63fb091c80188ec51f53514d07de907c1dd3d61d >> Author: Stephen Rothwell <sfr@...> >> Date: Wed Nov 15 16:44:31 2017 +1100 >> Add linux-next specific files for 20171115 >> >> and it crashes during boot with: > > The line: > > membarrier_mm_sync_core_before_usermode(mm); > > should be > > membarrier_mm_sync_core_before_usermode(current->mm); > > Given that we want to check the flags on the next mm at this point. > > I'll run this through KASAN and update the patchset.
Actually "mm" is prev_mm and is the right mm. I just needed to move this call before mmdrop(mm). I'm currently booting and running the selftests with kasan enabled and it works fine now. I'll update the patch.
Thanks!
Mathieu
> > Thanks! > > Mathieu > > >> >> ================================================================== >> BUG: KASAN: use-after-free in __read_once_size >> include/linux/compiler.h:183 [inline] >> BUG: KASAN: use-after-free in atomic_read >> arch/x86/include/asm/atomic.h:27 [inline] >> BUG: KASAN: use-after-free in membarrier_mm_sync_core_before_usermode >> include/linux/sched/mm.h:216 [inline] >> BUG: KASAN: use-after-free in finish_task_switch+0x61f/0x7c0 >> kernel/sched/core.c:2712 >> Read of size 4 at addr ffff880064fe5170 by task rc/1535 >> >> CPU: 0 PID: 1535 Comm: rc Not tainted 4.14.0-next-20171115 #22 >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:17 [inline] >> dump_stack+0x194/0x257 lib/dump_stack.c:53 >> 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_load4_noabort+0x14/0x20 mm/kasan/report.c:429 >> __read_once_size include/linux/compiler.h:183 [inline] >> atomic_read arch/x86/include/asm/atomic.h:27 [inline] >> membarrier_mm_sync_core_before_usermode include/linux/sched/mm.h:216 [inline] >> finish_task_switch+0x61f/0x7c0 kernel/sched/core.c:2712 >> schedule_tail+0xe/0x100 kernel/sched/core.c:2789 >> ret_from_fork+0x8/0x30 arch/x86/entry/entry_64.S:422 >> RIP: 0033:0x7fee2a8fdf46 >> RSP: 002b:00007ffddfd435b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 >> RAX: 0000000000000000 RBX: 00007ffddfd435b0 RCX: 00007fee2a8fdf46 >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 >> RBP: 00007ffddfd435f0 R08: 0000000000000000 R09: 00000000000005fc >> R10: 00007fee2adf59d0 R11: 0000000000000246 R12: 0000000000000000 >> R13: 0000000000000000 R14: 0000000000415d62 R15: 0000000000000001 >> >> Allocated by task 1532: >> 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 >> kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 >> kmem_cache_alloc+0x12e/0x760 mm/slab.c:3548 >> dup_mm kernel/fork.c:1230 [inline] >> copy_mm+0x30a/0x1310 kernel/fork.c:1293 >> copy_process.part.36+0x1f31/0x4d70 kernel/fork.c:1797 >> copy_process kernel/fork.c:1610 [inline] >> _do_fork+0x1ef/0xff0 kernel/fork.c:2091 >> SYSC_clone kernel/fork.c:2201 [inline] >> SyS_clone+0x37/0x50 kernel/fork.c:2195 >> do_syscall_64+0x26c/0x920 arch/x86/entry/common.c:286 >> return_from_SYSCALL_64+0x0/0x75 >> >> Freed by task 1535: >> 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:3492 [inline] >> kmem_cache_free+0x77/0x280 mm/slab.c:3750 >> __mmdrop+0x242/0x3d0 kernel/fork.c:604 >> mmdrop+0x28/0x30 kernel/fork.c:610 >> finish_task_switch+0x204/0x7c0 kernel/sched/core.c:2711 >> schedule_tail+0xe/0x100 kernel/sched/core.c:2789 >> ret_from_fork+0x8/0x30 arch/x86/entry/entry_64.S:422 >> >> The buggy address belongs to the object at ffff880064fe4d00 >> which belongs to the cache mm_struct of size 1368 >> The buggy address is located 1136 bytes inside of >> 1368-byte region [ffff880064fe4d00, ffff880064fe5258) >> The buggy address belongs to the page: >> page:ffffea000193f900 count:1 mapcount:0 mapping:ffff880064fe4100 >> index:0x0 compound_mapcount: 0 >> flags: 0x1fffc0000008100(slab|head) >> raw: 01fffc0000008100 ffff880064fe4100 0000000000000000 0000000100000005 >> raw: ffffea000193eba0 ffff88006c9f8f50 ffff88006c9f7b40 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff880064fe5000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff880064fe5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>>ffff880064fe5100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff880064fe5180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff880064fe5200: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc >> ================================================================== > > -- > Mathieu Desnoyers > EfficiOS Inc. > http://www.efficios.com
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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