syzbot


KASAN: use-after-free Read in do_sync_mmap_readahead

Status: upstream: reported on 2022/05/25 14:26
Reported-by: syzbot+5b96d55e5b54924c77ad@syzkaller.appspotmail.com
Fix commit: dcfa24ba6899 filemap: Cache the value of vm_flags
Patched on: [ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak 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 ci-upstream-kmsan-gce-386 ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-qemu2-riscv64]
First crash: 36d, last: 36d

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in do_sync_mmap_readahead+0x465/0x9f0 mm/filemap.c:3006
Read of size 8 at addr ffff88801fedb050 by task syz-executor.5/1755

CPU: 0 PID: 1755 Comm: syz-executor.5 Not tainted 5.18.0-rc7-syzkaller-00136-g3b5e1590a267 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description+0x65/0x4b0 mm/kasan/report.c:313
 print_report+0xf4/0x210 mm/kasan/report.c:429
 kasan_report+0xfb/0x130 mm/kasan/report.c:491
 do_sync_mmap_readahead+0x465/0x9f0 mm/filemap.c:3006
 filemap_fault+0x349/0xf20 mm/filemap.c:3138
 __do_fault+0x139/0x4f0 mm/memory.c:3915
 do_read_fault mm/memory.c:4240 [inline]
 do_fault mm/memory.c:4369 [inline]
 handle_pte_fault mm/memory.c:4627 [inline]
 __handle_mm_fault mm/memory.c:4763 [inline]
 handle_mm_fault+0x2bbb/0x3940 mm/memory.c:4861
 faultin_page mm/gup.c:878 [inline]
 __get_user_pages+0x4fd/0x1150 mm/gup.c:1099
 populate_vma_page_range+0x216/0x2b0 mm/gup.c:1442
 __mm_populate+0x2ea/0x4d0 mm/gup.c:1555
 mm_populate include/linux/mm.h:2701 [inline]
 vm_mmap_pgoff+0x241/0x2f0 mm/util.c:524
 ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7faf9f4890e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fafa06c9168 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007faf9f59bf60 RCX: 00007faf9f4890e9
RDX: 0000000001000006 RSI: 0000000000b34900 RDI: 0000000020000000
RBP: 00007faf9f4e308d R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff03616e1f R14: 00007fafa06c9300 R15: 0000000000022000
 </TASK>

Allocated by task 1755:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:436 [inline]
 __kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:469
 kasan_slab_alloc include/linux/kasan.h:224 [inline]
 slab_post_alloc_hook mm/slab.h:749 [inline]
 slab_alloc_node mm/slub.c:3217 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x199/0x2f0 mm/slub.c:3242
 vm_area_alloc+0x20/0xe0 kernel/fork.c:459
 mmap_region+0xbef/0x1730 mm/mmap.c:1771
 do_mmap+0x7a7/0xdf0 mm/mmap.c:1582
 vm_mmap_pgoff+0x1e5/0x2f0 mm/util.c:519
 ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 1759:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0xd8/0x110 mm/kasan/common.c:366
 kasan_slab_free include/linux/kasan.h:200 [inline]
 slab_free_hook mm/slub.c:1728 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1754
 slab_free mm/slub.c:3510 [inline]
 kmem_cache_free+0xc7/0x270 mm/slub.c:3527
 remove_vma mm/mmap.c:189 [inline]
 remove_vma_list mm/mmap.c:2625 [inline]
 __do_munmap+0x1b4f/0x1cd0 mm/mmap.c:2863
 do_munmap mm/mmap.c:2871 [inline]
 munmap_vma_range mm/mmap.c:604 [inline]
 mmap_region+0x97a/0x1730 mm/mmap.c:1746
 do_mmap+0x7a7/0xdf0 mm/mmap.c:1582
 vm_mmap_pgoff+0x1e5/0x2f0 mm/util.c:519
 ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801fedb000
 which belongs to the cache vm_area_struct of size 200
The buggy address is located 80 bytes inside of
 200-byte region [ffff88801fedb000, ffff88801fedb0c8)

The buggy address belongs to the physical page:
page:ffffea00007fb6c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fedb
memcg:ffff88801b6a0001
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 dead000000000100 dead000000000122 ffff888140006a00
raw: 0000000000000000 00000000000f000f 00000001ffffffff ffff88801b6a0001
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 20293, tgid 20293 (modprobe), ts 461559890566, free_ts 461429792689
 prep_new_page mm/page_alloc.c:2441 [inline]
 get_page_from_freelist+0x72e/0x7a0 mm/page_alloc.c:4182
 __alloc_pages+0x26c/0x5f0 mm/page_alloc.c:5408
 alloc_slab_page+0x70/0xf0 mm/slub.c:1799
 allocate_slab+0x5e/0x560 mm/slub.c:1944
 new_slab mm/slub.c:2004 [inline]
 ___slab_alloc+0x41e/0xcd0 mm/slub.c:3005
 __slab_alloc mm/slub.c:3092 [inline]
 slab_alloc_node mm/slub.c:3183 [inline]
 slab_alloc mm/slub.c:3225 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3232 [inline]
 kmem_cache_alloc+0x246/0x2f0 mm/slub.c:3242
 vm_area_alloc+0x20/0xe0 kernel/fork.c:459
 mmap_region+0xbef/0x1730 mm/mmap.c:1771
 do_mmap+0x7a7/0xdf0 mm/mmap.c:1582
 vm_mmap_pgoff+0x1e5/0x2f0 mm/util.c:519
 ksys_mmap_pgoff+0x48c/0x6d0 mm/mmap.c:1628
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1356 [inline]
 free_pcp_prepare+0x812/0x900 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3328 [inline]
 free_unref_page_list+0x12c/0x890 mm/page_alloc.c:3460
 release_pages+0x2a04/0x2cb0 mm/swap.c:980
 __pagevec_release+0x7d/0xf0 mm/swap.c:1000
 pagevec_release include/linux/pagevec.h:82 [inline]
 folio_batch_release include/linux/pagevec.h:146 [inline]
 truncate_inode_pages_range+0x4a2/0x17b0 mm/truncate.c:373
 kill_bdev block/bdev.c:77 [inline]
 blkdev_flush_mapping+0x181/0x350 block/bdev.c:656
 blkdev_put_whole block/bdev.c:687 [inline]
 blkdev_put+0x49f/0x790 block/bdev.c:947
 blkdev_close+0x55/0x80 block/fops.c:512
 __fput+0x3b9/0x820 fs/file_table.c:317
 task_work_run+0x146/0x1c0 kernel/task_work.c:164
 exit_task_work include/linux/task_work.h:37 [inline]
 do_exit+0x547/0x1eb0 kernel/exit.c:795
 do_group_exit+0x23b/0x2f0 kernel/exit.c:925
 get_signal+0x172f/0x1780 kernel/signal.c:2864
 arch_do_signal_or_restart+0x8d/0x750 arch/x86/kernel/signal.c:867
 exit_to_user_mode_loop+0x74/0x160 kernel/entry/common.c:166
 exit_to_user_mode_prepare+0xad/0x110 kernel/entry/common.c:201

Memory state around the buggy address:
 ffff88801fedaf00: fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc
 ffff88801fedaf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801fedb000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff88801fedb080: fb fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc
 ffff88801fedb100: fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-smack-root 2022/05/21 14:11 upstream 3b5e1590a267 7268fa62 .config log report info KASAN: use-after-free Read in do_sync_mmap_readahead