loop4: detected capacity change from 0 to 1024
EXT4-fs: inline encryption not supported
EXT4-fs (loop4): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: use-after-free in ext4_ext_correct_indexes+0x72/0x5b0 fs/ext4/extents.c:1712
Read of size 8 at addr ffff888033dcdb50 by task syz.4.21/6068

CPU: 0 UID: 0 PID: 6068 Comm: syz.4.21 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 ext4_ext_correct_indexes+0x72/0x5b0 fs/ext4/extents.c:1712
 ext4_ext_insert_extent+0x2007/0x4b50 fs/ext4/extents.c:2191
 ext4_ext_map_blocks+0x1696/0x58b0 fs/ext4/extents.c:4457
 ext4_map_create_blocks+0x11d/0x540 fs/ext4/inode.c:616
 ext4_map_blocks+0x7cd/0x11d0 fs/ext4/inode.c:809
 _ext4_get_block+0x1e3/0x470 fs/ext4/inode.c:909
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:942
 ext4_block_write_begin+0xb14/0x1950 fs/ext4/inode.c:1196
 ext4_write_begin+0xb40/0x18c0 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x355/0xd90 fs/ext4/inode.c:3123
 generic_perform_write+0x2af/0x8b0 mm/filemap.c:4314
 ext4_buffered_write_iter+0xd0/0x3a0 fs/ext4/file.c:300
 ext4_file_write_iter+0x299/0x1c10 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x629/0xba0 fs/read_write.c:688
 ksys_pwrite64 fs/read_write.c:795 [inline]
 __do_sys_pwrite64 fs/read_write.c:803 [inline]
 __se_sys_pwrite64 fs/read_write.c:800 [inline]
 __x64_sys_pwrite64+0x19c/0x230 fs/read_write.c:800
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5de535c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5de49be028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f5de55d5fa0 RCX: 00007f5de535c629
RDX: 000000000000fdef RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007f5de53f2b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000c00 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5de55d6038 R14: 00007f5de55d5fa0 R15: 00007ffc4d9d4748
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888033dcd240 pfn:0x33dcd
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: ffff888033dcd240 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5658, tgid 5658 (rm), ts 75595158920, free_ts 115590523637
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3255 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3444
 new_slab mm/slub.c:3502 [inline]
 refill_objects+0x334/0x3c0 mm/slub.c:7134
 refill_sheaf mm/slub.c:2804 [inline]
 __prefill_sheaf_pfmemalloc mm/slub.c:4895 [inline]
 kmem_cache_prefill_sheaf+0x31b/0x540 mm/slub.c:4984
 mt_get_sheaf lib/maple_tree.c:189 [inline]
 mas_alloc_nodes+0x1c2/0x350 lib/maple_tree.c:1140
 mas_preallocate+0x2d6/0x640 lib/maple_tree.c:5194
 vma_iter_prealloc mm/vma.h:568 [inline]
 __mmap_new_vma mm/vma.c:2526 [inline]
 __mmap_region mm/vma.c:2759 [inline]
 mmap_region+0x129e/0x2230 mm/vma.c:2837
 do_mmap+0xc2f/0x10c0 mm/mmap.c:559
 vm_mmap_pgoff+0x2cc/0x4f0 mm/util.c:581
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5912 tgid 5912 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfe3/0x1170 mm/page_alloc.c:2978
 __slab_free+0x24f/0x2a0 mm/slub.c:5532
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4501 [inline]
 slab_alloc_node mm/slub.c:4830 [inline]
 kmem_cache_alloc_node_noprof+0x22a/0x6e0 mm/slub.c:4882
 __alloc_skb+0x1d0/0x7d0 net/core/skbuff.c:702
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:289
 uevent_net_broadcast_tagged lib/kobject_uevent.c:352 [inline]
 kobject_uevent_net_broadcast+0x184/0x560 lib/kobject_uevent.c:413
 kobject_uevent_env+0x55f/0x9e0 lib/kobject_uevent.c:608
 device_add+0x557/0xb80 drivers/base/core.c:3670
 device_create_groups_vargs drivers/base/core.c:4371 [inline]
 device_create+0x269/0x300 drivers/base/core.c:4410
 macvtap_device_event+0x2dc/0x400 drivers/net/macvtap.c:176
 notifier_call_chain+0x1be/0x400 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
 call_netdevice_notifiers net/core/dev.c:2301 [inline]
 register_netdevice+0x1751/0x1d10 net/core/dev.c:11449
 macvlan_common_newlink+0x12af/0x1a40 drivers/net/macvlan.c:1546

Memory state around the buggy address:
 ffff888033dcda00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888033dcda80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888033dcdb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff888033dcdb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888033dcdc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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