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

Status: upstream: reported on 2025/01/06 01:43
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+b7694c9988ea48719f93@syzkaller.appspotmail.com
First crash: 6d12h, last: 1d01h
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node 0 (1) 2025/01/06 01:43

Sample crash report:
BTRFS info (device loop0): balance: start -d -m
BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
BTRFS info (device loop0): relocating block group 5242880 flags data|metadata
==================================================================
BUG: KASAN: slab-use-after-free in list_empty include/linux/list.h:373 [inline]
BUG: KASAN: slab-use-after-free in btrfs_backref_cleanup_node+0x2ea/0x4a0 fs/btrfs/backref.c:3154
Read of size 8 at addr ffff888052e67350 by task syz.0.0/5337

CPU: 0 UID: 0 PID: 5337 Comm: syz.0.0 Not tainted 6.13.0-rc6-syzkaller-00036-gfbfd64d25c7a #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 list_empty include/linux/list.h:373 [inline]
 btrfs_backref_cleanup_node+0x2ea/0x4a0 fs/btrfs/backref.c:3154
 btrfs_backref_release_cache+0xbb/0x720 fs/btrfs/backref.c:3180
 relocate_block_group+0xabf/0xd40 fs/btrfs/relocation.c:3741
 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 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: 0033:0x7fd1b3b85d29
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd1b497a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fd1b3d76160 RCX: 00007fd1b3b85d29
RDX: 0000000020000180 RSI: 00000000c4009420 RDI: 0000000000000008
RBP: 00007fd1b3c01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fd1b3d76160 R15: 00007ffcfa9c9f68
 </TASK>

Allocated by task 5337:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4329
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 btrfs_backref_alloc_node fs/btrfs/backref.c:3040 [inline]
 handle_indirect_tree_backref fs/btrfs/backref.c:3397 [inline]
 btrfs_backref_add_tree_node+0x16d2/0x2ed0 fs/btrfs/backref.c:3567
 build_backref_tree+0x2bc/0xf30 fs/btrfs/relocation.c:434
 relocate_tree_blocks+0x790/0x1dd0 fs/btrfs/relocation.c:2705
 relocate_block_group+0x755/0xd40 fs/btrfs/relocation.c:3686
 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 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

Freed by task 5337:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2353 [inline]
 slab_free mm/slub.c:4613 [inline]
 kfree+0x196/0x430 mm/slub.c:4761
 btrfs_backref_release_cache+0x5a/0x720 fs/btrfs/backref.c:3174
 relocate_block_group+0xabf/0xd40 fs/btrfs/relocation.c:3741
 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
 btrfs_balance+0xbdc/0x10c0 fs/btrfs/volumes.c:4655
 btrfs_ioctl_balance+0x493/0x7c0 fs/btrfs/ioctl.c:3670
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 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

The buggy address belongs to the object at ffff888052e67300
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 80 bytes inside of
 freed 128-byte region [ffff888052e67300, ffff888052e67380)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888052e67b00 pfn:0x52e67
flags: 0x4fff00000000200(workingset|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000200 ffff88801ac41a00 ffffea00010dff90 ffffea0001114b10
raw: ffff888052e67b00 000000000010000b 00000001f5000000 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 0x52c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5337, tgid 5317 (syz.0.0), ts 60709205609, free_ts 60505355451
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1558
 prep_new_page mm/page_alloc.c:1566 [inline]
 get_page_from_freelist+0x365c/0x37a0 mm/page_alloc.c:3476
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4753
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2269
 alloc_slab_page+0x6a/0x110 mm/slub.c:2423
 allocate_slab+0x5a/0x2b0 mm/slub.c:2589
 new_slab mm/slub.c:2642 [inline]
 ___slab_alloc+0xc27/0x14a0 mm/slub.c:3830
 __slab_alloc+0x58/0xa0 mm/slub.c:3920
 __slab_alloc_node mm/slub.c:3995 [inline]
 slab_alloc_node mm/slub.c:4156 [inline]
 __kmalloc_cache_noprof+0x27b/0x390 mm/slub.c:4324
 kmalloc_noprof include/linux/slab.h:901 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 btrfs_backref_alloc_node fs/btrfs/backref.c:3040 [inline]
 handle_direct_tree_backref fs/btrfs/backref.c:3263 [inline]
 btrfs_backref_add_tree_node+0xf43/0x2ed0 fs/btrfs/backref.c:3558
 build_backref_tree+0x2bc/0xf30 fs/btrfs/relocation.c:434
 relocate_tree_blocks+0x790/0x1dd0 fs/btrfs/relocation.c:2705
 relocate_block_group+0x755/0xd40 fs/btrfs/relocation.c:3686
 btrfs_relocate_block_group+0x77d/0xd90 fs/btrfs/relocation.c:4087
 btrfs_relocate_chunk+0x12c/0x3b0 fs/btrfs/volumes.c:3494
 __btrfs_balance+0x1b0f/0x26b0 fs/btrfs/volumes.c:4278
page last free pid 5298 tgid 5298 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xd3f/0x1010 mm/page_alloc.c:2659
 discard_slab mm/slub.c:2688 [inline]
 __put_partials+0x160/0x1c0 mm/slub.c:3157
 put_cpu_partial+0x17c/0x250 mm/slub.c:3232
 __slab_free+0x290/0x380 mm/slub.c:4483
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4119 [inline]
 slab_alloc_node mm/slub.c:4168 [inline]
 kmem_cache_alloc_noprof+0x1d9/0x380 mm/slub.c:4175
 getname_flags+0xb7/0x540 fs/namei.c:139
 do_sys_openat2+0xd2/0x1d0 fs/open.c:1396
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_openat fs/open.c:1433 [inline]
 __se_sys_openat fs/open.c:1428 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1428
 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

Memory state around the buggy address:
 ffff888052e67200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888052e67280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888052e67300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888052e67380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888052e67400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/07 12:13 upstream fbfd64d25c7a f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/07 04:21 upstream fbfd64d25c7a f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/07 04:13 upstream fbfd64d25c7a f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/05 12:57 upstream ab75170520d4 f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/05 11:51 upstream ab75170520d4 f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/04 05:57 upstream 63676eefb7a0 f3558dbf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/03 22:05 upstream 0bc21e701a6f 96d578a3 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/03 07:46 upstream 0bc21e701a6f d3ccff63 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
2025/01/02 01:33 upstream 56e6a3499e14 d3ccff63 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node
* Struck through repros no longer work on HEAD.