On Fri, Oct 27, 2017 at 11:44 AM, syzbot <bot+998c483ca801a50e3ce5b63a845216588ada5e2a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hello, > > syzkaller hit the following crash on > a31cc455c512f3f1dd5f79cac8e29a7c8a617af8 > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.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 Last happened on upstream f34157878d3b17641ad2366988600c23c89d98b2 (Oct 26) ================================================================== BUG: KASAN: use-after-free in handle_userfault+0x2076/0x23a0 fs/userfaultfd.c:371 Read of size 8 at addr ffff8801c9f33160 by task syz-executor5/13866 CPU: 1 PID: 13866 Comm: syz-executor5 Not tainted 4.14.0-rc6+ #147 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_load8_noabort+0x14/0x20 mm/kasan/report.c:430 handle_userfault+0x2076/0x23a0 fs/userfaultfd.c:371 do_anonymous_page mm/memory.c:3135 [inline] handle_pte_fault mm/memory.c:3908 [inline] __handle_mm_fault+0x3823/0x39c0 mm/memory.c:4034 handle_mm_fault+0x334/0x8d0 mm/memory.c:4071 __do_page_fault+0x5bd/0xd60 arch/x86/mm/fault.c:1444 do_page_fault+0xee/0x720 arch/x86/mm/fault.c:1520 page_fault+0x22/0x30 arch/x86/entry/entry_64.S:1066 RIP: 0010:__clear_user+0x42/0x70 arch/x86/lib/usercopy_64.c:23 RSP: 0000:ffff8801cbe3fb88 EFLAGS: 00010202 RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000008 RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000020038e40 RBP: ffff8801cbe3fb98 R08: 0000000000000001 R09: 1ffff100397c7f4d R10: ffff8801cbe3fa30 R11: 0000000000000000 R12: 0000000020038e40 R13: ffff8801cc622580 R14: 0000000020038c40 R15: 00007ffffffff000 copy_xregs_to_user arch/x86/include/asm/fpu/internal.h:371 [inline] copy_fpregs_to_sigframe arch/x86/kernel/fpu/signal.c:125 [inline] copy_fpstate_to_sigframe+0x196/0x470 arch/x86/kernel/fpu/signal.c:176 get_sigframe arch/x86/kernel/signal.c:283 [inline] __setup_rt_frame arch/x86/kernel/signal.c:464 [inline] setup_rt_frame arch/x86/kernel/signal.c:698 [inline] handle_signal arch/x86/kernel/signal.c:742 [inline] do_signal+0x9f6/0x1ee0 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158 prepare_exit_to_usermode+0x273/0x2d0 arch/x86/entry/common.c:197 retint_user+0x8/0x20 RIP: 0033: (null) RSP: 002b:0000000020039008 EFLAGS: 00010217 RAX: 0000000000000000 RBX: 0000000000758020 RCX: 0000000000452869 RDX: 0000000020059ffc RSI: 0000000020039000 RDI: 0000000000000400 RBP: 0000000000000045 R08: 0000000020058ffd R09: 0000000000000000 R10: 0000000020058ffc R11: 0000000000000212 R12: 00000000006ee718 R13: 00000000ffffffff R14: 00007f94a95396d4 R15: 0000000000000000 Allocated by task 13844: 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 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3561 dup_userfaultfd+0x21c/0x890 fs/userfaultfd.c:659 dup_mmap kernel/fork.c:662 [inline] dup_mm kernel/fork.c:1201 [inline] copy_mm+0xa38/0x1310 kernel/fork.c:1255 copy_process.part.39+0x1ea3/0x4af0 kernel/fork.c:1757 copy_process kernel/fork.c:1570 [inline] _do_fork+0x1ef/0xfb0 kernel/fork.c:2049 SYSC_clone kernel/fork.c:2159 [inline] SyS_clone+0x37/0x50 kernel/fork.c:2153 do_syscall_64+0x26c/0x8d0 arch/x86/entry/common.c:287 return_from_SYSCALL_64+0x0/0x7a Freed by task 13844: 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] kmem_cache_free+0x77/0x280 mm/slab.c:3763 userfaultfd_ctx_put+0x50c/0x740 fs/userfaultfd.c:165 userfaultfd_event_wait_completion+0x788/0x9c0 fs/userfaultfd.c:605 dup_fctx fs/userfaultfd.c:693 [inline] dup_userfaultfd_complete+0x2de/0x480 fs/userfaultfd.c:701 dup_mmap kernel/fork.c:730 [inline] dup_mm kernel/fork.c:1201 [inline] copy_mm+0xe9b/0x1310 kernel/fork.c:1255 copy_process.part.39+0x1ea3/0x4af0 kernel/fork.c:1757 copy_process kernel/fork.c:1570 [inline] _do_fork+0x1ef/0xfb0 kernel/fork.c:2049 SYSC_clone kernel/fork.c:2159 [inline] SyS_clone+0x37/0x50 kernel/fork.c:2153 do_syscall_64+0x26c/0x8d0 arch/x86/entry/common.c:287 return_from_SYSCALL_64+0x0/0x7a The buggy address belongs to the object at ffff8801c9f33000 which belongs to the cache userfaultfd_ctx_cache of size 360 The buggy address is located 352 bytes inside of 360-byte region [ffff8801c9f33000, ffff8801c9f33168) The buggy address belongs to the page: page:ffffea000727ccc0 count:1 mapcount:0 mapping:ffff8801c9f33000 index:0xffff8801c9f33ff7 flags: 0x200000000000100(slab) raw: 0200000000000100 ffff8801c9f33000 ffff8801c9f33ff7 0000000100000007 raw: ffffea0007473820 ffffea00071fb220 ffff8801d64d2300 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801c9f33000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801c9f33080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801c9f33100: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc ^ ffff8801c9f33180: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff8801c9f33200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== > BUG: KASAN: use-after-free in handle_userfault+0x206f/0x2390 > fs/userfaultfd.c:371 > Read of size 8 at addr ffff8801ce9cad88 by task syzkaller547101/2993 > > CPU: 0 PID: 2993 Comm: syzkaller547101 Not tainted 4.13.0-next-20170911+ #19 > 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+0x24e/0x340 mm/kasan/report.c:409 > __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430 > handle_userfault+0x206f/0x2390 fs/userfaultfd.c:371 > do_anonymous_page mm/memory.c:3095 [inline] > handle_pte_fault mm/memory.c:3908 [inline] > __handle_mm_fault+0x2d46/0x39c0 mm/memory.c:4034 > handle_mm_fault+0x334/0x8d0 mm/memory.c:4071 > __do_page_fault+0x4f6/0xb60 arch/x86/mm/fault.c:1445 > do_page_fault+0xee/0x720 arch/x86/mm/fault.c:1520 > page_fault+0x22/0x30 arch/x86/entry/entry_64.S:1066 > RIP: 0033:0x445455 > RSP: 002b:0000000020013000 EFLAGS: 00010217 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000445449 > RDX: 0000000020059ffc RSI: 0000000020013000 RDI: 0000000000000400 > RBP: 0000000000000000 R08: 0000000020058ffd R09: 00007f14ef18c700 > R10: 0000000020058ffc R11: 0000000000000202 R12: 0000000000000000 > R13: 00007ffca43554df R14: 00007f14ef18c9c0 R15: 0000000000000000 > > Allocated by task 2991: > 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 > kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 > kmem_cache_alloc+0x12e/0x760 mm/slab.c:3561 > dup_userfaultfd+0x21c/0x890 fs/userfaultfd.c:653 > dup_mmap kernel/fork.c:658 [inline] > dup_mm kernel/fork.c:1179 [inline] > copy_mm+0xa38/0x1310 kernel/fork.c:1233 > copy_process.part.36+0x1eae/0x4af0 kernel/fork.c:1735 > copy_process kernel/fork.c:1548 [inline] > _do_fork+0x1ef/0xfe0 kernel/fork.c:2027 > SYSC_clone kernel/fork.c:2137 [inline] > SyS_clone+0x37/0x50 kernel/fork.c:2131 > do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287 > return_from_SYSCALL_64+0x0/0x7a > > Freed by task 2991: > 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] > kmem_cache_free+0x77/0x280 mm/slab.c:3763 > userfaultfd_ctx_put+0x50c/0x740 fs/userfaultfd.c:165 > userfaultfd_event_wait_completion+0x754/0x910 fs/userfaultfd.c:599 > dup_fctx fs/userfaultfd.c:687 [inline] > dup_userfaultfd_complete+0x2de/0x480 fs/userfaultfd.c:695 > dup_mmap kernel/fork.c:726 [inline] > dup_mm kernel/fork.c:1179 [inline] > copy_mm+0xe9b/0x1310 kernel/fork.c:1233 > copy_process.part.36+0x1eae/0x4af0 kernel/fork.c:1735 > copy_process kernel/fork.c:1548 [inline] > _do_fork+0x1ef/0xfe0 kernel/fork.c:2027 > SYSC_clone kernel/fork.c:2137 [inline] > SyS_clone+0x37/0x50 kernel/fork.c:2131 > do_syscall_64+0x26c/0x8c0 arch/x86/entry/common.c:287 > return_from_SYSCALL_64+0x0/0x7a > > The buggy address belongs to the object at ffff8801ce9cac00 > which belongs to the cache userfaultfd_ctx_cache of size 400 > The buggy address is located 392 bytes inside of > 400-byte region [ffff8801ce9cac00, ffff8801ce9cad90) > The buggy address belongs to the page: > page:ffffea00073a7280 count:1 mapcount:0 mapping:ffff8801ce9ca000 > index:0xffff8801cf2f5300 > flags: 0x200000000000100(slab) > raw: 0200000000000100 ffff8801ce9ca000 ffff8801cf2f5300 0000000100000008 > raw: ffff8801d56d6f50 ffff8801d56d6f50 ffff8801d56d2600 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801ce9cac80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801ce9cad00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> >> ffff8801ce9cad80: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc > > ^ > ffff8801ce9cae00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801ce9cae80: 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 syzkaller@xxxxxxxxxxxxxxxx. > > 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. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/001a114c9224e34a49055c842032%40google.com. > For more options, visit https://groups.google.com/d/optout.
