syzbot


KASAN: use-after-free Read in mprotect_fixup

Status: upstream: reported C repro on 2022/07/11 06:41
Reported-by: syzbot+b707736a1ad47fda6500@syzkaller.appspotmail.com
First crash: 39d, last: 10d

Cause bisection: introduced by (bisect log) :
commit 2ee236fe53a8e2ab54679c74e8a1fb77e55b29bb
Author: Liam R. Howlett <Liam.Howlett@Oracle.com>
Date: Tue Jun 21 20:46:53 2022 +0000

  mm: start tracking VMAs with maple tree

Crash: KASAN: use-after-free Read in mprotect_fixup (log)
Repro: C syz .config

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in mprotect_fixup+0x8fc/0x960 mm/mprotect.c:606
Read of size 8 at addr ffff88801f89ed80 by task syz-executor107/3608

CPU: 0 PID: 3608 Comm: syz-executor107 Not tainted 5.19.0-rc4-next-20220628-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:317 [inline]
 print_report.cold+0x2ba/0x719 mm/kasan/report.c:433
 kasan_report+0xbe/0x1f0 mm/kasan/report.c:495
 mprotect_fixup+0x8fc/0x960 mm/mprotect.c:606
 do_mprotect_pkey+0x70f/0xa80 mm/mprotect.c:781
 __do_sys_pkey_mprotect mm/mprotect.c:816 [inline]
 __se_sys_pkey_mprotect mm/mprotect.c:813 [inline]
 __x64_sys_pkey_mprotect+0x93/0xf0 mm/mprotect.c:813
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
RIP: 0033:0x7fb254db5389
Code: 28 c3 e8 1a 17 00 00 66 2e 0f 1f 84 00 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcd8258c98 EFLAGS: 00000246 ORIG_RAX: 0000000000000149
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007fb254db5389
RDX: 0000000000000000 RSI: 0000000000003000 RDI: 0000000020ffd000
RBP: 0000000000000003 R08: 0000000000000001 R09: 0000000038303633
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffcd8258da0
R13: 00007ffcd8258cc0 R14: 00007fb254df10a1 R15: 0000000000000000
 </TASK>

Allocated by task 3608:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 __kasan_slab_alloc+0x90/0xc0 mm/kasan/common.c:469
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:736 [inline]
 slab_alloc_node mm/slub.c:3243 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3258 [inline]
 kmem_cache_alloc+0x2d6/0x4c0 mm/slub.c:3268
 vm_area_dup+0x81/0x380 kernel/fork.c:466
 __split_vma+0x9f/0x530 mm/mmap.c:2276
 split_vma+0x9f/0xe0 mm/mmap.c:2335
 mprotect_fixup+0x6c7/0x960 mm/mprotect.c:607
 do_mprotect_pkey+0x70f/0xa80 mm/mprotect.c:781
 __do_sys_pkey_mprotect mm/mprotect.c:816 [inline]
 __se_sys_pkey_mprotect mm/mprotect.c:813 [inline]
 __x64_sys_pkey_mprotect+0x93/0xf0 mm/mprotect.c:813
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 3608:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
 kasan_set_track+0x21/0x30 mm/kasan/common.c:45
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free+0x166/0x1c0 mm/kasan/common.c:328
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1754 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1780
 slab_free mm/slub.c:3534 [inline]
 kmem_cache_free+0xeb/0x5b0 mm/slub.c:3551
 __vma_adjust+0x9ab/0x1900 mm/mmap.c:889
 vma_merge+0x590/0x870 mm/mmap.c:1122
 mprotect_fixup+0x338/0x960 mm/mprotect.c:595
 do_mprotect_pkey+0x70f/0xa80 mm/mprotect.c:781
 __do_sys_pkey_mprotect mm/mprotect.c:816 [inline]
 __se_sys_pkey_mprotect mm/mprotect.c:813 [inline]
 __x64_sys_pkey_mprotect+0x93/0xf0 mm/mprotect.c:813
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

The buggy address belongs to the object at ffff88801f89ed80
 which belongs to the cache vm_area_struct of size 152
The buggy address is located 0 bytes inside of
 152-byte region [ffff88801f89ed80, ffff88801f89ee18)

The buggy address belongs to the physical page:
page:ffffea00007e2780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1f89e
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff888140006b40
raw: 0000000000000000 0000000080120012 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 3603, tgid 3603 (sshd), ts 50397360264, free_ts 45063905366
 prep_new_page mm/page_alloc.c:2535 [inline]
 get_page_from_freelist+0x210d/0x3a30 mm/page_alloc.c:4282
 __alloc_pages+0x1c7/0x510 mm/page_alloc.c:5506
 alloc_pages+0x1aa/0x310 mm/mempolicy.c:2280
 alloc_slab_page mm/slub.c:1824 [inline]
 allocate_slab+0x27e/0x3d0 mm/slub.c:1969
 new_slab mm/slub.c:2029 [inline]
 ___slab_alloc+0x89d/0xef0 mm/slub.c:3031
 __slab_alloc.constprop.0+0x4d/0xa0 mm/slub.c:3118
 slab_alloc_node mm/slub.c:3209 [inline]
 slab_alloc mm/slub.c:3251 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3258 [inline]
 kmem_cache_alloc+0x3fb/0x4c0 mm/slub.c:3268
 vm_area_dup+0x81/0x380 kernel/fork.c:466
 dup_mmap+0x642/0x1070 kernel/fork.c:640
 dup_mm+0x91/0x370 kernel/fork.c:1520
 copy_mm kernel/fork.c:1569 [inline]
 copy_process+0x3ca8/0x7080 kernel/fork.c:2237
 kernel_clone+0xe7/0xab0 kernel/fork.c:2652
 __do_sys_clone+0xba/0x100 kernel/fork.c:2786
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1453 [inline]
 free_pcp_prepare+0x5e4/0xd20 mm/page_alloc.c:1503
 free_unref_page_prepare mm/page_alloc.c:3383 [inline]
 free_unref_page_list+0x16f/0xb90 mm/page_alloc.c:3525
 release_pages+0xbe8/0x1810 mm/swap.c:1017
 tlb_batch_pages_flush+0xa8/0x1a0 mm/mmu_gather.c:58
 tlb_flush_mmu_free mm/mmu_gather.c:255 [inline]
 tlb_flush_mmu mm/mmu_gather.c:262 [inline]
 tlb_finish_mmu+0x147/0x7e0 mm/mmu_gather.c:353
 exit_mmap+0x1fe/0x720 mm/mmap.c:3212
 __mmput+0x128/0x4c0 kernel/fork.c:1180
 mmput+0x5c/0x70 kernel/fork.c:1201
 exit_mm kernel/exit.c:510 [inline]
 do_exit+0xa09/0x29f0 kernel/exit.c:782
 do_group_exit+0xd2/0x2f0 kernel/exit.c:925
 __do_sys_exit_group kernel/exit.c:936 [inline]
 __se_sys_exit_group kernel/exit.c:934 [inline]
 __x64_sys_exit_group+0x3a/0x50 kernel/exit.c:934
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Memory state around the buggy address:
 ffff88801f89ec80: fc fc fc fc fc 00 00 00 00 00 00 00 00 00 00 00
 ffff88801f89ed00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
>ffff88801f89ed80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88801f89ee00: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801f89ee80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (5):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-linux-next-kasan-gce-root 2022/07/08 23:59 linux-next cb71b93c2dc3 b5765a15 .config log report syz C KASAN: use-after-free Read in mprotect_fixup
ci-upstream-linux-next-kasan-gce-root 2022/08/07 06:21 linux-next cb71b93c2dc3 88e3a122 .config log report info KASAN: use-after-free Read in mprotect_fixup
ci-upstream-linux-next-kasan-gce-root 2022/07/28 10:04 linux-next cb71b93c2dc3 fb95c74d .config log report info KASAN: use-after-free Read in mprotect_fixup
ci-upstream-linux-next-kasan-gce-root 2022/07/19 05:19 linux-next cb71b93c2dc3 ff988920 .config log report info KASAN: use-after-free Read in mprotect_fixup
ci-upstream-linux-next-kasan-gce-root 2022/07/08 23:27 linux-next cb71b93c2dc3 b5765a15 .config log report info KASAN: use-after-free Read in mprotect_fixup