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

Status: upstream: reported on 2025/01/20 16:45
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+45212e9d87a98c3f5b42@syzkaller.appspotmail.com
First crash: 6d11h, last: 6d11h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] KASAN: slab-use-after-free Read in join_transaction 2 (3) 2025/01/20 17:11

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in join_transaction+0xd9b/0xda0 fs/btrfs/transaction.c:278
Read of size 4 at addr ffff888011839024 by task kworker/u4:9/1128

CPU: 0 UID: 0 PID: 1128 Comm: kworker/u4:9 Not tainted 6.13.0-rc7-syzkaller-00019-gc45323b7560e #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound btrfs_async_reclaim_data_space
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
 join_transaction+0xd9b/0xda0 fs/btrfs/transaction.c:278
 start_transaction+0xaf8/0x1670 fs/btrfs/transaction.c:697
 flush_space+0x448/0xcf0 fs/btrfs/space-info.c:803
 btrfs_async_reclaim_data_space+0x159/0x510 fs/btrfs/space-info.c:1321
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
 worker_thread+0x870/0xd30 kernel/workqueue.c:3398
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Allocated by task 5315:
 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]
 join_transaction+0x144/0xda0 fs/btrfs/transaction.c:308
 start_transaction+0xaf8/0x1670 fs/btrfs/transaction.c:697
 btrfs_create_common+0x1b2/0x2e0 fs/btrfs/inode.c:6572
 lookup_open fs/namei.c:3649 [inline]
 open_last_lookups fs/namei.c:3748 [inline]
 path_openat+0x1c03/0x3590 fs/namei.c:3984
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_creat fs/open.c:1495 [inline]
 __se_sys_creat fs/open.c:1489 [inline]
 __x64_sys_creat+0x123/0x170 fs/open.c:1489
 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 5336:
 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
 cleanup_transaction fs/btrfs/transaction.c:2063 [inline]
 btrfs_commit_transaction+0x2c97/0x3720 fs/btrfs/transaction.c:2598
 insert_balance_item+0x1284/0x20b0 fs/btrfs/volumes.c:3757
 btrfs_balance+0x992/0x10c0 fs/btrfs/volumes.c:4633
 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 ffff888011839000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 36 bytes inside of
 freed 2048-byte region [ffff888011839000, ffff888011839800)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11838
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801ac42000 ffffea0000493400 dead000000000002
raw: 0000000000000000 0000000000080008 00000001f5000000 0000000000000000
head: 00fff00000000040 ffff88801ac42000 ffffea0000493400 dead000000000002
head: 0000000000000000 0000000000080008 00000001f5000000 0000000000000000
head: 00fff00000000003 ffffea0000460e01 ffffffffffffffff 0000000000000000
head: 0000000000000008 0000000000000000 00000000ffffffff 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 57, tgid 57 (kworker/0:2), ts 67248182943, free_ts 67229742023
 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+0x3e1/0x780 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]
 __do_kmalloc_node mm/slub.c:4297 [inline]
 __kmalloc_node_track_caller_noprof+0x2e9/0x4c0 mm/slub.c:4317
 kmalloc_reserve+0x111/0x2a0 net/core/skbuff.c:609
 __alloc_skb+0x1f3/0x440 net/core/skbuff.c:678
 alloc_skb include/linux/skbuff.h:1323 [inline]
 alloc_skb_with_frags+0xc3/0x820 net/core/skbuff.c:6612
 sock_alloc_send_pskb+0x91a/0xa60 net/core/sock.c:2884
 sock_alloc_send_skb include/net/sock.h:1803 [inline]
 mld_newpack+0x1c3/0xaf0 net/ipv6/mcast.c:1747
 add_grhead net/ipv6/mcast.c:1850 [inline]
 add_grec+0x1492/0x19a0 net/ipv6/mcast.c:1988
 mld_send_cr net/ipv6/mcast.c:2114 [inline]
 mld_ifc_work+0x691/0xd90 net/ipv6/mcast.c:2651
page last free pid 5300 tgid 5300 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
 __slab_free+0x2c2/0x380 mm/slub.c:4524
 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]
 __do_kmalloc_node mm/slub.c:4297 [inline]
 __kmalloc_noprof+0x236/0x4c0 mm/slub.c:4310
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1037 [inline]
 fib_create_info+0xc14/0x25b0 net/ipv4/fib_semantics.c:1435
 fib_table_insert+0x1f6/0x1f20 net/ipv4/fib_trie.c:1231
 fib_magic+0x3d8/0x620 net/ipv4/fib_frontend.c:1112
 fib_add_ifaddr+0x40c/0x5e0 net/ipv4/fib_frontend.c:1156
 fib_netdev_event+0x375/0x490 net/ipv4/fib_frontend.c:1494
 notifier_call_chain+0x1a5/0x3f0 kernel/notifier.c:85
 __dev_notify_flags+0x207/0x400
 dev_change_flags+0xf0/0x1a0 net/core/dev.c:9045
 do_setlink+0xc90/0x4210 net/core/rtnetlink.c:3109
 rtnl_changelink net/core/rtnetlink.c:3723 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3875 [inline]
 rtnl_newlink+0x1bb6/0x2210 net/core/rtnetlink.c:4012

Memory state around the buggy address:
 ffff888011838f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888011838f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888011839000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888011839080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888011839100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/01/14 11:41 upstream c45323b7560e 0dce2409 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in join_transaction
* Struck through repros no longer work on HEAD.