==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_ext_correct_indexes+0x92/0x540 fs/ext4/extents.c:1717
Read of size 8 at addr ffff88811f65ed70 by task syz.2.1961/10936

CPU: 0 PID: 10936 Comm: syz.2.1961 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
 print_address_description+0x71/0x200 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:420
 kasan_report+0x122/0x150 mm/kasan/report.c:524
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351
 ext4_ext_correct_indexes+0x92/0x540 fs/ext4/extents.c:1717
 ext4_ext_insert_extent+0x21b5/0x47d0 fs/ext4/extents.c:2178
 ext4_ext_map_blocks+0x1869/0x61d0 fs/ext4/extents.c:4361
 ext4_map_blocks+0x9d8/0x1b70 fs/ext4/inode.c:679
 _ext4_get_block+0x1ea/0x540 fs/ext4/inode.c:822
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:839
 ext4_block_write_begin+0x506/0x10c0 fs/ext4/inode.c:1124
 ext4_write_begin+0x600/0xf90 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3000
 generic_perform_write+0x30a/0x5d0 mm/filemap.c:3862
 ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285
 ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1
 __kernel_write_iter+0x296/0x660 fs/read_write.c:517
 dump_emit_page fs/coredump.c:950 [inline]
 dump_user_range+0x40b/0x660 fs/coredump.c:977
 elf_core_dump+0x2b52/0x3060 fs/binfmt_elf.c:2354
 do_coredump+0x163f/0x22b0 fs/coredump.c:824
 get_signal+0x11db/0x1520 kernel/signal.c:2857
 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x10 kernel/entry/common.c:316
 irqentry_exit+0x12/0x40 kernel/entry/common.c:419
 exc_page_fault+0x5e/0xb0 arch/x86/mm/fault.c:1490
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f686e59aec1
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000000000000030 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f686e815fa0 RCX: 00007f686e59aeb9
RDX: 0000000000000000 RSI: 0000000000000030 RDI: 0000000000000600
RBP: 00007f686e608c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f686e816038 R14: 00007f686e815fa0 R15: 00007ffc6fbf7a68
 </TASK>

Allocated by task 10926:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:329
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:737
 slab_alloc_node mm/slub.c:3359 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x16e/0x2d0 mm/slub.c:3383
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 __kernfs_new_node+0xe3/0x6b0 fs/kernfs/dir.c:614
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:690
 __kernfs_create_file+0x4e/0x270 fs/kernfs/file.c:1068
 sysfs_add_file_mode_ns+0x1ce/0x270 fs/sysfs/file.c:294
 sysfs_create_file_ns+0x128/0x1b0 fs/sysfs/file.c:355
 sysfs_create_file include/linux/sysfs.h:623 [inline]
 device_create_file drivers/base/core.c:3055 [inline]
 device_add+0x4d0/0xee0 drivers/base/core.c:3641
 netdev_register_kobject+0x16b/0x320 net/core/net-sysfs.c:2013
 register_netdevice+0x10de/0x1830 net/core/dev.c:10204
 register_netdev+0x3e/0x50 net/core/dev.c:10332
 ip6gre_init_net+0x2b1/0x3b0 net/ipv6/ip6_gre.c:1655
 ops_init+0x1c8/0x4a0 net/core/net_namespace.c:138
 setup_net+0x507/0xde0 net/core/net_namespace.c:336
 copy_net_ns+0x35a/0x5c0 net/core/net_namespace.c:508
 create_new_namespaces+0x3a2/0x660 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x120/0x170 kernel/nsproxy.c:226
 ksys_unshare+0x4ba/0x7c0 kernel/fork.c:3277
 __do_sys_unshare kernel/fork.c:3348 [inline]
 __se_sys_unshare kernel/fork.c:3346 [inline]
 __x64_sys_unshare+0x38/0x40 kernel/fork.c:3346
 x64_sys_call+0x767/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:273
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88811f65ecc0
 which belongs to the cache kernfs_node_cache of size 128
The buggy address is located 48 bytes to the right of
 128-byte region [ffff88811f65ecc0, ffff88811f65ed40)

The buggy address belongs to the physical page:
page:ffffea00047d9780 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11f65e
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000122 ffff8881001b2640
raw: 0000000000000000 0000000000150015 00000001ffffffff 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 10926, tgid 10926 (syz-executor), ts 381329744236, free_ts 381010372679
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1d0/0x1f0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x2e56/0x2ee0 mm/page_alloc.c:4328
 __alloc_pages+0x242/0x4c0 mm/page_alloc.c:5614
 alloc_slab_page include/linux/gfp.h:-1 [inline]
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0xec/0x4b0 mm/slub.c:1997
 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3154
 __slab_alloc+0x5e/0xa0 mm/slub.c:3240
 slab_alloc_node mm/slub.c:3325 [inline]
 slab_alloc mm/slub.c:3367 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3374 [inline]
 kmem_cache_alloc+0x1ab/0x2d0 mm/slub.c:3383
 kmem_cache_zalloc include/linux/slab.h:689 [inline]
 __kernfs_new_node+0xe3/0x6b0 fs/kernfs/dir.c:614
 kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:690
 __kernfs_create_file+0x4e/0x270 fs/kernfs/file.c:1068
 sysfs_add_file_mode_ns+0x1ce/0x270 fs/sysfs/file.c:294
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x4a1/0xd10 fs/sysfs/group.c:148
 sysfs_create_group+0x1f/0x30 fs/sysfs/group.c:174
 netdev_queue_add_kobject net/core/net-sysfs.c:1670 [inline]
 netdev_queue_update_kobjects+0x214/0x470 net/core/net-sysfs.c:1716
 register_queue_kobjects net/core/net-sysfs.c:1777 [inline]
 netdev_register_kobject+0x268/0x320 net/core/net-sysfs.c:2017
 register_netdevice+0x10de/0x1830 net/core/dev.c:10204
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1532 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3384
 free_unref_page+0x33/0x390 mm/page_alloc.c:3479
 free_the_page mm/page_alloc.c:754 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:5703
 __vunmap+0x9c0/0xb80 mm/vmalloc.c:2726
 free_work+0x5a/0x80 mm/vmalloc.c:97
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2292
 worker_thread+0xa26/0x11e0 kernel/workqueue.c:2439
 kthread+0x281/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
 ffff88811f65ec00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811f65ec80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
>ffff88811f65ed00: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                                             ^
 ffff88811f65ed80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811f65ee00: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop2): ext4_ext_correct_indexes:1721: inode #18: comm syz.2.1961: ex 0000000000000000 == NULL or eh 0000000000000001 == NULL
EXT4-fs error (device loop2): mb_free_blocks:1826: group 0, inode 18: block 177:freeing already freed block (bit 11); block bitmap corrupt.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 10936 at mm/page_alloc.c:3861 next_zones_zonelist include/linux/mmzone.h:1480 [inline]
WARNING: CPU: 0 PID: 10936 at mm/page_alloc.c:3861 get_page_from_freelist+0x2c82/0x2ee0 mm/page_alloc.c:4227
Modules linked in:

CPU: 0 PID: 10936 Comm: syz.2.1961 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rmqueue mm/page_alloc.c:3861 [inline]
RIP: 0010:get_page_from_freelist+0x2c82/0x2ee0 mm/page_alloc.c:4325
Code: e8 13 62 04 00 48 be 00 00 00 00 00 fc ff df e9 44 d5 ff ff 89 de e8 6d 4b f4 ff 48 be 00 00 00 00 00 fc ff df 49 89 c5 eb bb <0f> 0b 83 7d b0 04 0f 82 b0 d6 ff ff e9 a1 d6 ff ff 48 89 df 48 89
RSP: 0018:ffffc900043065c0 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffffc900043067b8 RCX: dffffc0000000000
RDX: ffffffff872ad540 RSI: 0000000000000007 RDI: ffffffff872ad8d8
RBP: ffffc90004306750 R08: ffffffff872adb57 R09: 1ffffffff0e55b6a
R10: dffffc0000000000 R11: fffffbfff0e55b6b R12: 0000000000000901
R13: ffffc900043067bc R14: ffffffff872ad501 R15: 0000000000148d40
FS:  00007f686f4386c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000030 CR3: 000000011f431000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __alloc_pages+0x242/0x4c0 mm/page_alloc.c:5614
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x9d/0x160 mm/slab_common.c:1077
 __do_kmalloc_node mm/slab_common.c:924 [inline]
 __kmalloc+0xe0/0x1e0 mm/slab_common.c:949
 kmalloc_array include/linux/slab.h:615 [inline]
 kcalloc include/linux/slab.h:646 [inline]
 ext4_ext_remove_space+0xafe/0x40d0 fs/ext4/extents.c:2920
 ext4_ext_truncate+0x200/0x320 fs/ext4/extents.c:4470
 ext4_truncate+0x9be/0xfb0 fs/ext4/inode.c:4295
 ext4_truncate_failed_write fs/ext4/truncate.h:22 [inline]
 ext4_write_begin+0xa6a/0xf90 fs/ext4/inode.c:1288
 ext4_da_write_begin+0x3e7/0x8c0 fs/ext4/inode.c:3000
 generic_perform_write+0x30a/0x5d0 mm/filemap.c:3862
 ext4_buffered_write_iter+0x367/0x630 fs/ext4/file.c:285
 ext4_file_write_iter+0x191/0x1500 fs/ext4/file.c:-1
 __kernel_write_iter+0x296/0x660 fs/read_write.c:517
 dump_emit_page fs/coredump.c:950 [inline]
 dump_user_range+0x40b/0x660 fs/coredump.c:977
 elf_core_dump+0x2b52/0x3060 fs/binfmt_elf.c:2354
 do_coredump+0x163f/0x22b0 fs/coredump.c:824
 get_signal+0x11db/0x1520 kernel/signal.c:2857
 arch_do_signal_or_restart+0xd1/0x1140 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x10 kernel/entry/common.c:316
 irqentry_exit+0x12/0x40 kernel/entry/common.c:419
 exc_page_fault+0x5e/0xb0 arch/x86/mm/fault.c:1490
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7f686e59aec1
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000000000000030 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f686e815fa0 RCX: 00007f686e59aeb9
RDX: 0000000000000000 RSI: 0000000000000030 RDI: 0000000000000600
RBP: 00007f686e608c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f686e816038 R14: 00007f686e815fa0 R15: 00007ffc6fbf7a68
 </TASK>
---[ end trace 0000000000000000 ]---
EXT4-fs error (device loop2): ext4_ext_remove_space:2930: inode #18: comm syz.2.1961: pblk 0 bad header/extent: invalid magic - magic 3b7, entries 1, max 4(0), depth 7778(7778)
EXT4-fs error (device loop2): ext4_ext_remove_space:2930: inode #18: comm syz.2.1961: pblk 0 bad header/extent: invalid magic - magic 3b7, entries 1, max 4(0), depth 7778(7778)
EXT4-fs error (device loop2): ext4_evict_inode:290: comm syz.2.1961: couldn't truncate inode 18 (err -117)