syzbot


KASAN: slab-use-after-free Read in finish_fault

Status: upstream: reported C repro on 2024/06/13 11:38
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+d6e5c328862b5ae6cbfe@syzkaller.appspotmail.com
Fix commit: mm-memory-extend-finish_fault-to-support-large-folio-fix
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-net-next-test-gce ci2-upstream-usb]
First crash: 35d, last: 29d
Cause bisection: introduced by (bisect log) :
commit 1c05047ad01693ad92bdf8347fad3b5c2b25e8bb
Author: Baolin Wang <baolin.wang@linux.alibaba.com>
Date: Tue Jun 4 10:17:45 2024 +0000

  mm: memory: extend finish_fault() to support large folio

Crash: KASAN: slab-use-after-free Read in finish_fault (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [mm?] KASAN: slab-use-after-free Read in finish_fault 2 (3) 2024/06/13 13:03

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in ptep_get include/linux/pgtable.h:317 [inline]
BUG: KASAN: use-after-free in ptep_get_lockless include/linux/pgtable.h:581 [inline]
BUG: KASAN: use-after-free in pte_range_none mm/memory.c:4409 [inline]
BUG: KASAN: use-after-free in finish_fault+0xf87/0x1460 mm/memory.c:4905
Read of size 8 at addr ffff88807bfb7000 by task syz-executor149/5117

CPU: 0 PID: 5117 Comm: syz-executor149 Not tainted 6.10.0-rc2-next-20240607-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:91 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:117
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 ptep_get include/linux/pgtable.h:317 [inline]
 ptep_get_lockless include/linux/pgtable.h:581 [inline]
 pte_range_none mm/memory.c:4409 [inline]
 finish_fault+0xf87/0x1460 mm/memory.c:4905
 do_read_fault mm/memory.c:5052 [inline]
 do_fault mm/memory.c:5178 [inline]
 do_pte_missing mm/memory.c:3948 [inline]
 handle_pte_fault+0x3db5/0x7130 mm/memory.c:5502
 __handle_mm_fault mm/memory.c:5645 [inline]
 handle_mm_fault+0x10df/0x1ba0 mm/memory.c:5810
 faultin_page mm/gup.c:1339 [inline]
 __get_user_pages+0x6ef/0x1590 mm/gup.c:1638
 populate_vma_page_range+0x264/0x330 mm/gup.c:2078
 __mm_populate+0x27a/0x460 mm/gup.c:2181
 mm_populate include/linux/mm.h:3442 [inline]
 __do_sys_remap_file_pages mm/mmap.c:3177 [inline]
 __se_sys_remap_file_pages+0x7a1/0x9a0 mm/mmap.c:3103
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff1cbb3e399
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff1cbad8238 EFLAGS: 00000246 ORIG_RAX: 00000000000000d8
RAX: ffffffffffffffda RBX: 00007ff1cbbc8318 RCX: 00007ff1cbb3e399
RDX: 0000000000000000 RSI: 0000000000200000 RDI: 00000000202ec000
RBP: 00007ff1cbbc8310 R08: 0000000000000000 R09: 00007ff1cbad86c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff1cbbc831c
R13: 0000000000000000 R14: 00007ffcff8e0350 R15: 00007ffcff8e0438
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7bfb7
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00007ed408 ffff8880b94448a0 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x440dc0(GFP_KERNEL_ACCOUNT|__GFP_COMP|__GFP_ZERO), pid 5097, tgid 5088 (syz-executor149), ts 55842453591, free_ts 55925905863
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1470
 prep_new_page mm/page_alloc.c:1478 [inline]
 get_page_from_freelist+0x2cbd/0x2d70 mm/page_alloc.c:3457
 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4715
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2263
 pagetable_alloc_noprof include/linux/mm.h:2881 [inline]
 __pte_alloc_one_noprof include/asm-generic/pgalloc.h:70 [inline]
 pte_alloc_one+0x88/0x5d0 arch/x86/mm/pgtable.c:33
 do_fault_around mm/memory.c:5000 [inline]
 do_read_fault mm/memory.c:5039 [inline]
 do_fault mm/memory.c:5178 [inline]
 do_pte_missing mm/memory.c:3948 [inline]
 handle_pte_fault+0x2ba7/0x7130 mm/memory.c:5502
 __handle_mm_fault mm/memory.c:5645 [inline]
 handle_mm_fault+0x10df/0x1ba0 mm/memory.c:5810
 faultin_page mm/gup.c:1339 [inline]
 __get_user_pages+0x6ef/0x1590 mm/gup.c:1638
 populate_vma_page_range+0x264/0x330 mm/gup.c:2078
 __mm_populate+0x27a/0x460 mm/gup.c:2181
 mm_populate include/linux/mm.h:3442 [inline]
 __do_sys_remap_file_pages mm/mmap.c:3177 [inline]
 __se_sys_remap_file_pages+0x7a1/0x9a0 mm/mmap.c:3103
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5097 tgid 5088 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1089 [inline]
 free_unref_folios+0x103a/0x1b00 mm/page_alloc.c:2669
 folios_put_refs+0x76e/0x860 mm/swap.c:1020
 free_pages_and_swap_cache+0x5c8/0x690 mm/swap_state.c:335
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
 tlb_flush_mmu+0x3a3/0x680 mm/mmu_gather.c:373
 tlb_finish_mmu+0xd4/0x200 mm/mmu_gather.c:465
 exit_mmap+0x44f/0xc80 mm/mmap.c:3395
 __mmput+0x115/0x390 kernel/fork.c:1341
 exit_mm+0x220/0x310 kernel/exit.c:565
 do_exit+0x9aa/0x28e0 kernel/exit.c:861
 do_group_exit+0x207/0x2c0 kernel/exit.c:1023
 get_signal+0x16a1/0x1740 kernel/signal.c:2909
 arch_do_signal_or_restart+0x96/0x830 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88807bfb6f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807bfb6f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807bfb7000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88807bfb7080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88807bfb7100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/09 14:36 linux-next d35b2284e966 82c05ab8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
2024/06/15 13:06 linux-next a957267fa7e9 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in finish_fault
2024/06/09 11:28 linux-next d35b2284e966 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in finish_fault
2024/06/15 13:57 linux-next a957267fa7e9 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
2024/06/15 03:11 linux-next a957267fa7e9 8d849073 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
2024/06/12 13:09 linux-next a957267fa7e9 4d75f4f7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
2024/06/12 12:09 linux-next a957267fa7e9 4d75f4f7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
2024/06/09 13:28 linux-next d35b2284e966 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: use-after-free Read in finish_fault
* Struck through repros no longer work on HEAD.