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BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:653 [inline]
BUG: KASAN: use-after-free in string+0x231/0x2b0 lib/vsprintf.c:735
Read of size 1 at addr ffff8880584374f7 by task syz.0.17/5999

CPU: 0 UID: 0 PID: 5999 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
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_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 string_nocheck lib/vsprintf.c:653 [inline]
 string+0x231/0x2b0 lib/vsprintf.c:735
 vsnprintf+0x739/0xf00 lib/vsprintf.c:2926
 bch2_prt_printf+0x1c6/0x740 fs/bcachefs/printbuf.c:183
 bch2_dirent_to_text+0x2bd/0xd20 fs/bcachefs/dirent.c:220
 __bch2_bkey_fsck_err+0x3f7/0x540 fs/bcachefs/error.c:691
 bch2_dirent_validate+0x7b3/0xfb0 fs/bcachefs/dirent.c:164
 bch2_bkey_val_validate+0x202/0x3e0 fs/bcachefs/bkey_methods.c:143
 btree_node_bkey_val_validate fs/bcachefs/btree_io.c:880 [inline]
 bch2_btree_node_read_done+0x4051/0x5550 fs/bcachefs/btree_io.c:1303
 btree_node_read_work+0x40e/0xe60 fs/bcachefs/btree_io.c:1440
 bch2_btree_node_read+0x887/0x2a00 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1906 [inline]
 bch2_btree_root_read+0x5f0/0x760 fs/bcachefs/btree_io.c:1928
 read_btree_roots+0x2c6/0x840 fs/bcachefs/recovery.c:615
 bch2_fs_recovery+0x261f/0x3a50 fs/bcachefs/recovery.c:1006
 bch2_fs_start+0xaaf/0xda0 fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0xb39/0x1520 fs/bcachefs/fs.c:2488
 vfs_get_tree+0x92/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4a0ad9038a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f4a0bc11e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4a0bc11ef0 RCX: 00007f4a0ad9038a
RDX: 0000200000000040 RSI: 0000200000004940 RDI: 00007f4a0bc11eb0
RBP: 0000200000000040 R08: 00007f4a0bc11ef0 R09: 0000000000004000
R10: 0000000000004000 R11: 0000000000000246 R12: 0000200000004940
R13: 00007f4a0bc11eb0 R14: 000000000000496e R15: 0000200000000000
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x345e pfn:0x58437
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 000000000000345e 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 31, tgid 31 (kworker/u4:2), ts 182184553962, free_ts 183598225023
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2660
 new_slab mm/slub.c:2714 [inline]
 ___slab_alloc+0xbeb/0x1420 mm/slub.c:3901
 __slab_alloc mm/slub.c:3992 [inline]
 __slab_alloc_node mm/slub.c:4067 [inline]
 slab_alloc_node mm/slub.c:4228 [inline]
 __do_kmalloc_node mm/slub.c:4375 [inline]
 __kmalloc_node_track_caller_noprof+0x2f8/0x4e0 mm/slub.c:4395
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:600
 __alloc_skb+0x142/0x2d0 net/core/skbuff.c:669
 alloc_skb include/linux/skbuff.h:1336 [inline]
 nsim_dev_trap_skb_build drivers/net/netdevsim/dev.c:763 [inline]
 nsim_dev_trap_report drivers/net/netdevsim/dev.c:820 [inline]
 nsim_dev_trap_report_work+0x29a/0xb80 drivers/net/netdevsim/dev.c:866
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5763 tgid 5763 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2895
 discard_slab mm/slub.c:2758 [inline]
 __put_partials+0x156/0x1a0 mm/slub.c:3223
 put_cpu_partial+0x17c/0x250 mm/slub.c:3298
 __slab_free+0x2d5/0x3c0 mm/slub.c:4565
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4191 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 __kmalloc_cache_noprof+0x1be/0x3d0 mm/slub.c:4402
 kmalloc_noprof include/linux/slab.h:905 [inline]
 netdevice_queue_work drivers/infiniband/core/roce_gid_mgmt.c:664 [inline]
 netdevice_event+0x3a1/0x8a0 drivers/infiniband/core/roce_gid_mgmt.c:823
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0x18d/0x2e0 net/core/dev.c:-1
 netif_change_flags+0xe8/0x1a0 net/core/dev.c:9617
 do_setlink+0xc55/0x41c0 net/core/rtnetlink.c:3143
 rtnl_changelink net/core/rtnetlink.c:3761 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3920 [inline]
 rtnl_newlink+0x160b/0x1c70 net/core/rtnetlink.c:4057
 rtnetlink_rcv_msg+0x7cc/0xb70 net/core/rtnetlink.c:6946
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2552

Memory state around the buggy address:
 ffff888058437380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888058437400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888058437480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff888058437500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888058437580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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