loop0: detected capacity change from 0 to 32768
bcachefs (loop0): starting version 1.7: mi_btree_bitmap opts=errors=continue,metadata_checksum=none,data_checksum=none,compression=lz4,nocow
  allowing incompatible features above 0.0: (unknown version)
  features: lz4,new_siphash,inline_data,new_extent_overwrite,btree_ptr_v2,new_varint,journal_no_flush,alloc_v2,extents_across_btree_nodes
bcachefs (loop0): Using encoding defined by superblock: utf8-12.1.0
bcachefs (loop0): initializing new filesystem
bcachefs (loop0): going read-write
bcachefs (loop0): marking superblocks
bcachefs (loop0): initializing freespace
bcachefs (loop0): done initializing freespace
bcachefs (loop0): reading snapshots table
bcachefs (loop0): reading snapshots done
bcachefs (loop0):  loop0: Superblock write was silently dropped! (seq 0 expected 42)
bcachefs (loop0): done starting filesystem
A link change request failed with some changes committed already. Interface bridge_slave_0 may have been left with an inconsistent configuration, please check.
==================================================================
BUG: KASAN: slab-out-of-bounds in ppp_async_encode drivers/net/ppp/ppp_async.c:579 [inline]
BUG: KASAN: slab-out-of-bounds in ppp_async_push+0xcd2/0x1bc0 drivers/net/ppp/ppp_async.c:675
Read of size 1 at addr ffff8880436960d0 by task syz.0.0/5353

CPU: 0 UID: 0 PID: 5353 Comm: syz.0.0 Not tainted 6.16.0-syzkaller-11952-g6e64f4580381 #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
 ppp_async_encode drivers/net/ppp/ppp_async.c:579 [inline]
 ppp_async_push+0xcd2/0x1bc0 drivers/net/ppp/ppp_async.c:675
 ppp_async_send+0xcc/0xf0 drivers/net/ppp/ppp_async.c:634
 ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2286 [inline]
 ppp_input+0x279/0x9f0 drivers/net/ppp/ppp_generic.c:2310
 pppoe_rcv_core+0xc4/0x2b0 drivers/net/ppp/pppoe.c:376
 sk_backlog_rcv include/net/sock.h:1148 [inline]
 __release_sock+0x24c/0x350 net/core/sock.c:3194
 release_sock+0x5f/0x1f0 net/core/sock.c:3748
 pppoe_sendmsg+0x137/0x790 drivers/net/ppp/pppoe.c:904
 sock_sendmsg_nosec net/socket.c:714 [inline]
 __sock_sendmsg+0x219/0x270 net/socket.c:729
 ____sys_sendmsg+0x52d/0x830 net/socket.c:2614
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2668
 __sys_sendmmsg+0x227/0x430 net/socket.c:2757
 __do_sys_sendmmsg net/socket.c:2784 [inline]
 __se_sys_sendmmsg net/socket.c:2781 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2781
 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: 0033:0x7fa9aa38ebe9
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:00007fa9a67ed038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007fa9aa5b5fa0 RCX: 00007fa9aa38ebe9
RDX: 0000000000000004 RSI: 0000200000009140 RDI: 0000000000000008
RBP: 00007fa9aa411e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa9aa5b6038 R14: 00007fa9aa5b5fa0 R15: 00007ffd98c522f8
 </TASK>

Allocated by task 5130:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:330 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:356
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4180 [inline]
 slab_alloc_node mm/slub.c:4229 [inline]
 kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4236
 anon_vma_alloc mm/rmap.c:94 [inline]
 __anon_vma_prepare+0x117/0x4a0 mm/rmap.c:202
 __vmf_anon_prepare mm/memory.c:3506 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_cow_fault mm/memory.c:5593 [inline]
 do_fault mm/memory.c:5709 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x4ca8/0x5440 mm/memory.c:6195
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

The buggy address belongs to the object at ffff888043696000
 which belongs to the cache anon_vma of size 208
The buggy address is located 0 bytes to the right of
 allocated 208-byte region [ffff888043696000, ffff8880436960d0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888043696770 pfn:0x43696
flags: 0x4fff00000000200(workingset|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000200 ffff888030413140 ffffea00010d0790 ffffea00010f3290
raw: ffff888043696770 00000000000f000e 00000000f5000000 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5040, tgid 5040 (sh), ts 44027783368, free_ts 44025848750
 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:2487 [inline]
 allocate_slab+0x8a/0x370 mm/slub.c:2655
 new_slab mm/slub.c:2709 [inline]
 ___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
 __slab_alloc mm/slub.c:3981 [inline]
 __slab_alloc_node mm/slub.c:4056 [inline]
 slab_alloc_node mm/slub.c:4217 [inline]
 kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4236
 anon_vma_alloc mm/rmap.c:94 [inline]
 __anon_vma_prepare+0x117/0x4a0 mm/rmap.c:202
 __vmf_anon_prepare mm/memory.c:3506 [inline]
 vmf_anon_prepare mm/internal.h:432 [inline]
 do_cow_fault mm/memory.c:5593 [inline]
 do_fault mm/memory.c:5709 [inline]
 do_pte_missing mm/memory.c:4234 [inline]
 handle_pte_fault mm/memory.c:6052 [inline]
 __handle_mm_fault+0x4ca8/0x5440 mm/memory.c:6195
 handle_mm_fault+0x40a/0x8e0 mm/memory.c:6364
 do_user_addr_fault+0xa81/0x1390 arch/x86/mm/fault.c:1336
 handle_page_fault arch/x86/mm/fault.c:1476 [inline]
 exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 15 tgid 15 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
 pagetable_free include/linux/mm.h:2898 [inline]
 pagetable_dtor_free include/linux/mm.h:2996 [inline]
 __tlb_remove_table+0x2d2/0x3b0 include/asm-generic/tlb.h:220
 __tlb_remove_table_free mm/mmu_gather.c:227 [inline]
 tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:290
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xca8/0x1770 kernel/rcu/tree.c:2861
 handle_softirqs+0x283/0x870 kernel/softirq.c:579
 run_ksoftirqd+0x9b/0x100 kernel/softirq.c:968
 smpboot_thread_fn+0x53f/0xa60 kernel/smpboot.c:160
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/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:
 ffff888043695f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888043696000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888043696080: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
                                                 ^
 ffff888043696100: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888043696180: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================