fragmentation     0
    bp_start          8
  
  incorrectly set at freespace:0:30:0 (free 0, genbits 0 should be 0), fixing
==================================================================
BUG: KASAN: slab-use-after-free in bch2_bucket_alloc_trans+0x1aa0/0x2410 fs/bcachefs/alloc_foreground.c:547
Read of size 8 at addr ffff888057cb6120 by task syz.2.215/6850

CPU: 1 UID: 0 PID: 6850 Comm: syz.2.215 Not tainted 6.16.0-rc1-next-20250611-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 bch2_bucket_alloc_trans+0x1aa0/0x2410 fs/bcachefs/alloc_foreground.c:547
 bch2_bucket_alloc_set_trans+0x5a6/0xe70 fs/bcachefs/alloc_foreground.c:728
 __open_bucket_add_buckets+0x1437/0x1e40 fs/bcachefs/alloc_foreground.c:925
 open_bucket_add_buckets+0x2ee/0x440 fs/bcachefs/alloc_foreground.c:957
 bch2_alloc_sectors_start_trans+0xd26/0x1e80 fs/bcachefs/alloc_foreground.c:-1
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
 bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
 bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
 bch2_btree_split_leaf+0x14b/0x8e0 fs/bcachefs/btree_update_interior.c:1911
 bch2_trans_commit_error+0x1b7/0x1130 fs/bcachefs/btree_trans_commit.c:911
 __bch2_trans_commit+0x1ce8/0x8880 fs/bcachefs/btree_trans_commit.c:1098
 bch2_trans_commit fs/bcachefs/btree_update.h:242 [inline]
 bch2_journal_replay+0x1789/0x2620 fs/bcachefs/recovery.c:396
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
 bch2_fs_recovery+0x26a1/0x39e0 fs/bcachefs/recovery.c:989
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1194
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 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: 0033:0x7f918e9900ca
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:00007f918f750e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f918f750ef0 RCX: 00007f918e9900ca
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 00007f918f750eb0
RBP: 00002000000000c0 R08: 00007f918f750ef0 R09: 0000000000818001
R10: 0000000000818001 R11: 0000000000000246 R12: 0000200000000080
R13: 00007f918f750eb0 R14: 000000000000596a R15: 0000200000000240
 </TASK>

Allocated by task 6850:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __do_kmalloc_node mm/slub.c:4328 [inline]
 __kmalloc_node_track_caller_noprof+0x271/0x4e0 mm/slub.c:4347
 __do_krealloc mm/slub.c:4905 [inline]
 krealloc_noprof+0x124/0x340 mm/slub.c:4958
 __bch2_trans_kmalloc+0x26c/0xc80 fs/bcachefs/btree_iter.c:3187
 bch2_trans_kmalloc_nomemzero_ip fs/bcachefs/btree_iter.h:586 [inline]
 bch2_trans_kmalloc_nomemzero fs/bcachefs/btree_iter.h:621 [inline]
 bch2_alloc_sectors_start_trans+0x1d59/0x1e80 fs/bcachefs/alloc_foreground.c:1250
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
 bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
 bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
 bch2_btree_split_leaf+0x14b/0x8e0 fs/bcachefs/btree_update_interior.c:1911
 bch2_trans_commit_error+0x1b7/0x1130 fs/bcachefs/btree_trans_commit.c:911
 __bch2_trans_commit+0x1ce8/0x8880 fs/bcachefs/btree_trans_commit.c:1098
 bch2_trans_commit fs/bcachefs/btree_update.h:242 [inline]
 bch2_journal_replay+0x1789/0x2620 fs/bcachefs/recovery.c:396
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
 bch2_fs_recovery+0x26a1/0x39e0 fs/bcachefs/recovery.c:989
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1194
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 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

Freed by task 6850:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2381 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x18e/0x440 mm/slub.c:4842
 krealloc_noprof+0x1cd/0x340 mm/slub.c:-1
 __bch2_trans_kmalloc+0x26c/0xc80 fs/bcachefs/btree_iter.c:3187
 bch2_trans_kmalloc_nomemzero_ip fs/bcachefs/btree_iter.h:586 [inline]
 bch2_trans_kmalloc_nomemzero fs/bcachefs/btree_iter.h:621 [inline]
 __bch2_trans_subbuf_alloc+0x2da/0x460 fs/bcachefs/btree_update.c:557
 bch2_trans_subbuf_alloc fs/bcachefs/btree_update.h:148 [inline]
 bch2_trans_jset_entry_alloc fs/bcachefs/btree_update.h:168 [inline]
 __bch2_trans_log_str fs/bcachefs/btree_update.c:814 [inline]
 bch2_trans_log_str+0xd5/0x3c0 fs/bcachefs/btree_update.c:827
 __bch2_fsck_err+0xc11/0xfb0 fs/bcachefs/error.c:625
 bch2_check_discard_freespace_key+0x71b/0xce0 fs/bcachefs/alloc_background.c:1436
 try_alloc_bucket fs/bcachefs/alloc_foreground.c:272 [inline]
 bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:420 [inline]
 bch2_bucket_alloc_trans+0x1333/0x2410 fs/bcachefs/alloc_foreground.c:544
 bch2_bucket_alloc_set_trans+0x5a6/0xe70 fs/bcachefs/alloc_foreground.c:728
 __open_bucket_add_buckets+0x1437/0x1e40 fs/bcachefs/alloc_foreground.c:925
 open_bucket_add_buckets+0x2ee/0x440 fs/bcachefs/alloc_foreground.c:957
 bch2_alloc_sectors_start_trans+0xd26/0x1e80 fs/bcachefs/alloc_foreground.c:-1
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
 bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
 bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
 bch2_btree_split_leaf+0x14b/0x8e0 fs/bcachefs/btree_update_interior.c:1911
 bch2_trans_commit_error+0x1b7/0x1130 fs/bcachefs/btree_trans_commit.c:911
 __bch2_trans_commit+0x1ce8/0x8880 fs/bcachefs/btree_trans_commit.c:1098
 bch2_trans_commit fs/bcachefs/btree_update.h:242 [inline]
 bch2_journal_replay+0x1789/0x2620 fs/bcachefs/recovery.c:396
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:485 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:540
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:611
 bch2_fs_recovery+0x26a1/0x39e0 fs/bcachefs/recovery.c:989
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1194
 bch2_fs_get_tree+0xb02/0x14f0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x92/0x2b0 fs/super.c:1802
 do_new_mount+0x24a/0xa40 fs/namespace.c:3885
 do_mount fs/namespace.c:4222 [inline]
 __do_sys_mount fs/namespace.c:4433 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4410
 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

The buggy address belongs to the object at ffff888057cb6000
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 288 bytes inside of
 freed 512-byte region [ffff888057cb6000, ffff888057cb6200)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57cb4
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea00015f2d01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5838, tgid 5838 (syz-executor), ts 95084264520, free_ts 30915366795
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 alloc_slab_page mm/slub.c:2451 [inline]
 allocate_slab+0x8a/0x3b0 mm/slub.c:2619
 new_slab mm/slub.c:2673 [inline]
 ___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
 __slab_alloc mm/slub.c:3949 [inline]
 __slab_alloc_node mm/slub.c:4024 [inline]
 slab_alloc_node mm/slub.c:4185 [inline]
 __do_kmalloc_node mm/slub.c:4327 [inline]
 __kmalloc_noprof+0x305/0x4f0 mm/slub.c:4340
 kmalloc_noprof include/linux/slab.h:909 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 fib6_info_alloc+0x30/0xf0 net/ipv6/ip6_fib.c:155
 ip6_route_info_create+0x142/0x860 net/ipv6/route.c:3764
 ip6_route_add+0x28/0x190 net/ipv6/route.c:3889
 addrconf_add_mroute net/ipv6/addrconf.c:2551 [inline]
 addrconf_add_dev+0x24f/0x340 net/ipv6/addrconf.c:2569
 inet6_addr_add+0x1a1/0xc00 net/ipv6/addrconf.c:3031
 inet6_rtm_newaddr+0x93d/0xd20 net/ipv6/addrconf.c:5063
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6944
 netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x758/0x8d0 net/netlink/af_netlink.c:1339
page last free pid 1 tgid 1 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
 __free_pages mm/page_alloc.c:5071 [inline]
 free_contig_range+0x1bd/0x4a0 mm/page_alloc.c:6927
 destroy_args+0x7e/0x5d0 mm/debug_vm_pgtable.c:1009
 debug_vm_pgtable+0x412/0x450 mm/debug_vm_pgtable.c:1389
 do_one_initcall+0x233/0x820 init/main.c:1274
 do_initcall_level+0x137/0x1f0 init/main.c:1336
 do_initcalls+0x69/0xd0 init/main.c:1352
 kernel_init_freeable+0x3d9/0x570 init/main.c:1584
 kernel_init+0x1d/0x1d0 init/main.c:1474
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff888057cb6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888057cb6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888057cb6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                               ^
 ffff888057cb6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888057cb6200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================