Message-ID: <677b3538.050a0220.3b53b0.0065.GAE@google.com>
Date: Sun, 05 Jan 2025 17:43:20 -0800
From: syzbot <syzbot+b7694c9988ea48719f93@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] KASAN: slab-use-after-free Read in btrfs_backref_cleanup_node

Hello,

syzbot found the following issue on:

HEAD commit:    ab75170520d4 Merge tag 'linux-watchdog-6.13-rc6' of git://..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128104b0580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1c541fa8af5c9cc7
dashboard link: https://syzkaller.appspot.com/bug?extid=b7694c9988ea48719f93
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-ab751705.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/81d0d11be3bd/vmlinux-ab751705.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1f076be686f8/bzImage-ab751705.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b7694c9988ea48719f93@...kaller.appspotmail.com

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 ffff888000d4f050 by task syz.0.0/5342

CPU: 0 UID: 0 PID: 5342 Comm: syz.0.0 Not tainted 6.13.0-rc5-syzkaller-00163-gab75170520d4 #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: 0033:0x7f3be4b85d29
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:00007f3be45dd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3be4d76160 RCX: 00007f3be4b85d29
RDX: 0000000020000180 RSI: 00000000c4009420 RDI: 0000000000000008
RBP: 00007f3be4c01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f3be4d76160 R15: 00007fff6101e6a8
 </TASK>

Allocated by task 5342:
 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 5342:
 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 ffff888000d4f000
 which belongs to the cache kmalloc-128 of size 128
The buggy address is located 80 bytes inside of
 freed 128-byte region [ffff888000d4f000, ffff888000d4f080)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xd4f
flags: 0x7ff00000000000(node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 007ff00000000000 ffff88801ac41a00 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 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 5342, tgid 5320 (syz.0.0), ts 78052212500, free_ts 77737190918
 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_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
page last free pid 5323 tgid 5323 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
 getname fs/namei.c:223 [inline]
 __do_sys_symlink fs/namei.c:4716 [inline]
 __se_sys_symlink fs/namei.c:4714 [inline]
 __x64_sys_symlink+0x5d/0x90 fs/namei.c:4714
 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:
 ffff888000d4ef00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888000d4ef80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888000d4f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                 ^
 ffff888000d4f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888000d4f100: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
==================================================================


---
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