KASAN: use-after-free Read in nilfs_segctor_sync

Status: fixed on 2023/02/24 13:50
Subsystems: nilfs
[Documentation on labels]
Reported-by: syzbot+f816fa82f8783f7a02bb@syzkaller.appspotmail.com
Fix commit: 8cccf05fe857 nilfs2: fix use-after-free bug of ns_writer on remount
First crash: 1367d, last: 1357d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[PATCH] nilfs2: fix use-after-free bug of ns_writer on remount 1 (1) 2022/11/04 14:29
[PATCH] nilfs: Avoid use-after-free caused by nilfs->ns_writer 2 (2) 2022/11/03 18:56
[syzbot] KASAN: use-after-free Read in nilfs_segctor_sync 0 (1) 2022/10/31 15:53
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 KASAN: use-after-free Read in nilfs_segctor_sync 19 syz, C 1 1254d 1365d 0/1 upstream: reported C repro on 2022/11/02 14:31

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
Read of size 8 at addr ffff888074e119b8 by task syz-executor345/3615

CPU: 1 PID: 3615 Comm: syz-executor345 Not tainted 6.1.0-rc4-syzkaller-00020-gf67dd6ce0723 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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:284 [inline]
 print_report+0x15e/0x45d mm/kasan/report.c:395
 kasan_report+0xbb/0x1f0 mm/kasan/report.c:495
 __lock_acquire+0x3ee7/0x56d0 kernel/locking/lockdep.c:4925
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162
 finish_wait+0xc0/0x270 kernel/sched/wait.c:406
 nilfs_segctor_sync+0x22d/0x300 fs/nilfs2/segment.c:2197
 nilfs_construct_segment fs/nilfs2/segment.c:2251 [inline]
 nilfs_transaction_commit+0x54c/0x930 fs/nilfs2/segment.c:285
 nilfs_rmdir+0x1f7/0x240 fs/nilfs2/namei.c:336
 vfs_rmdir.part.0+0x1b0/0x5a0 fs/namei.c:4120
 vfs_rmdir fs/namei.c:4105 [inline]
 do_rmdir+0x3a6/0x430 fs/namei.c:4181
 __do_sys_rmdir fs/namei.c:4200 [inline]
 __se_sys_rmdir fs/namei.c:4198 [inline]
 __x64_sys_rmdir+0xc6/0x110 fs/namei.c:4198
 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+0x63/0xcd
RIP: 0033:0x7fc34eb96199
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:00007fc34eb412f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000054
RAX: ffffffffffffffda RBX: 00007fc34ec1d4a0 RCX: 00007fc34eb96199
RDX: 00007fc34eb96199 RSI: 00000000000f4240 RDI: 0000000020000040
RBP: 00007fc34ebe8730 R08: 0000000000000000 R09: 0000000000000000
R10: 00007fc34eb416b8 R11: 0000000000000246 R12: 00007fc34ebe8308
R13: 00007fc34ebe80c8 R14: 0030656c69662f2e R15: 00007fc34ec1d4a8
 </TASK>

Allocated by task 3615:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 ____kasan_kmalloc mm/kasan/common.c:330 [inline]
 __kasan_kmalloc+0xa1/0xb0 mm/kasan/common.c:380
 kmalloc include/linux/slab.h:553 [inline]
 kzalloc include/linux/slab.h:689 [inline]
 nilfs_segctor_new fs/nilfs2/segment.c:2657 [inline]
 nilfs_attach_log_writer+0x13e/0xa80 fs/nilfs2/segment.c:2786
 nilfs_fill_super fs/nilfs2/super.c:1073 [inline]
 nilfs_mount+0xb7e/0xfb0 fs/nilfs2/super.c:1317
 legacy_get_tree+0x105/0x220 fs/fs_context.c:610
 vfs_get_tree+0x89/0x2f0 fs/super.c:1531
 do_new_mount fs/namespace.c:3040 [inline]
 path_mount+0x1326/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 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+0x63/0xcd

Freed by task 3634:
 kasan_save_stack+0x1e/0x40 mm/kasan/common.c:45
 kasan_set_track+0x21/0x30 mm/kasan/common.c:52
 kasan_save_free_info+0x2a/0x40 mm/kasan/generic.c:511
 ____kasan_slab_free mm/kasan/common.c:236 [inline]
 ____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1724 [inline]
 slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1750
 slab_free mm/slub.c:3661 [inline]
 __kmem_cache_free+0xab/0x3b0 mm/slub.c:3674
 nilfs_segctor_destroy fs/nilfs2/segment.c:2756 [inline]
 nilfs_detach_log_writer+0x597/0x9f0 fs/nilfs2/segment.c:2813
 nilfs_attach_log_writer+0xe1/0xa80 fs/nilfs2/segment.c:2783
 nilfs_remount+0x36c/0x4c0 fs/nilfs2/super.c:1171
 legacy_reconfigure+0x115/0x180 fs/fs_context.c:633
 reconfigure_super+0x408/0xa30 fs/super.c:935
 do_remount fs/namespace.c:2702 [inline]
 path_mount+0x182c/0x1e20 fs/namespace.c:3362
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 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+0x63/0xcd

The buggy address belongs to the object at ffff888074e11800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 440 bytes inside of
 1024-byte region [ffff888074e11800, ffff888074e11c00)

The buggy address belongs to the physical page:
page:ffffea0001d38400 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x74e10
head:ffffea0001d38400 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888011841dc0
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 3621, tgid 3616 (syz-executor345), ts 45591231520, free_ts 45350796593
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x10b5/0x2d50 mm/page_alloc.c:4288
 __alloc_pages+0x1c7/0x5a0 mm/page_alloc.c:5555
 alloc_pages+0x1a6/0x270 mm/mempolicy.c:2285
 alloc_slab_page mm/slub.c:1794 [inline]
 allocate_slab+0x213/0x300 mm/slub.c:1939
 new_slab mm/slub.c:1992 [inline]
 ___slab_alloc+0xa91/0x1400 mm/slub.c:3180
 __slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3279
 slab_alloc_node mm/slub.c:3364 [inline]
 __kmem_cache_alloc_node+0x191/0x3e0 mm/slub.c:3437
 __do_kmalloc_node mm/slab_common.c:954 [inline]
 __kmalloc+0x46/0xc0 mm/slab_common.c:968
 kmalloc include/linux/slab.h:558 [inline]
 kzalloc include/linux/slab.h:689 [inline]
 alloc_workqueue+0x963/0x1020 kernel/workqueue.c:4314
 loop_configure+0x1579/0x19e0 drivers/block/loop.c:1061
 lo_ioctl+0x278/0x18e0 drivers/block/loop.c:1550
 blkdev_ioctl+0x36e/0x800 block/ioctl.c:614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
 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+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare+0x65c/0xd90 mm/page_alloc.c:1509
 free_unref_page_prepare mm/page_alloc.c:3387 [inline]
 free_unref_page+0x19/0x4d0 mm/page_alloc.c:3483
 __unfreeze_partials+0x17c/0x1a0 mm/slub.c:2586
 qlink_free mm/kasan/quarantine.c:168 [inline]
 qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x62/0x80 mm/kasan/common.c:302
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slab.h:737 [inline]
 slab_alloc_node mm/slub.c:3398 [inline]
 slab_alloc mm/slub.c:3406 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3413 [inline]
 kmem_cache_alloc+0x2ac/0x3c0 mm/slub.c:3422
 getname_flags.part.0+0x50/0x4f0 fs/namei.c:139
 getname_flags include/linux/audit.h:320 [inline]
 getname+0x8e/0xd0 fs/namei.c:218
 do_sys_openat2+0xf5/0x4c0 fs/open.c:1304
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1337
 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+0x63/0xcd

Memory state around the buggy address:
 ffff888074e11880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888074e11900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888074e11980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff888074e11a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888074e11a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/11/10 13:19 upstream f67dd6ce0723 b2488a87 .config console log report syz C [mounted in repro] ci-upstream-kasan-gce-root KASAN: use-after-free Read in nilfs_segctor_sync
2022/10/31 11:32 upstream b229b6ca5abb 2a71366b .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: use-after-free Read in nilfs_segctor_sync
2022/10/31 11:18 upstream b229b6ca5abb 2a71366b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: use-after-free Read in nilfs_segctor_sync
* Struck through repros no longer work on HEAD.