loop1: detected capacity change from 0 to 128
EXT4-fs (loop1): mounted filesystem without journal. Quota mode: none.
ext4 filesystem being mounted at /0/file0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa supports timestamps until 2038-01-19 (0x7fffffff)
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
Read of size 4 at addr ffff88811cc0f20c by task syz.1.975/3082

CPU: 0 PID: 3082 Comm: syz.1.975 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
 ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
 ext4_ext_remove_space+0x2de/0x40d0 fs/ext4/extents.c:2834
 ext4_punch_hole+0x77c/0xbd0 fs/ext4/inode.c:4147
 ext4_fallocate+0x2b6/0x1dc0 fs/ext4/extents.c:4767
 vfs_fallocate+0x4c5/0x5a0 fs/open.c:324
 madvise_remove mm/madvise.c:1049 [inline]
 madvise_vma_behavior mm/madvise.c:1073 [inline]
 madvise_walk_vmas mm/madvise.c:1308 [inline]
 do_madvise+0x1423/0x3290 mm/madvise.c:1487
 __do_sys_madvise mm/madvise.c:1500 [inline]
 __se_sys_madvise mm/madvise.c:1498 [inline]
 __x64_sys_madvise+0xa9/0xc0 mm/madvise.c:1498
 x64_sys_call+0x99e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:29
 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
RIP: 0033:0x7f156a99aef9
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:00007f156b897028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f156ac05fa0 RCX: 00007f156a99aef9
RDX: 0000000000000009 RSI: 000000000060000b RDI: 0000200000000000
RBP: 00007f156aa2fee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f156ac06038 R14: 00007f156ac05fa0 R15: 00007ffe4cca9078
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00047303c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11cc0f
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea00044d5308 ffffea00046f5208 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x102dc2(GFP_HIGHUSER|__GFP_NOWARN|__GFP_ZERO), pid 3073, tgid 3072 (syz.0.971), ts 318558710961, free_ts 318663571605
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2670
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2677
 get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4583
 __alloc_pages+0x1fa/0x610 mm/page_alloc.c:5924
 vm_area_alloc_pages mm/vmalloc.c:-1 [inline]
 __vmalloc_area_node mm/vmalloc.c:3084 [inline]
 __vmalloc_node_range+0x8bf/0x1430 mm/vmalloc.c:3256
 vmalloc_user+0x73/0x80 mm/vmalloc.c:3410
 security_read_policy+0xe9/0x220 security/selinux/ss/services.c:4042
 sel_open_policy+0x217/0x4a0 security/selinux/selinuxfs.c:423
 do_dentry_open+0x88e/0x1260 fs/open.c:884
 vfs_open+0x73/0x80 fs/open.c:1017
 do_open fs/namei.c:3633 [inline]
 path_openat+0x2700/0x2f80 fs/namei.c:3790
 do_filp_open+0x1f1/0x430 fs/namei.c:3817
 do_sys_openat2+0x15e/0x810 fs/open.c:1343
 do_sys_open fs/open.c:1359 [inline]
 __do_sys_openat fs/open.c:1375 [inline]
 __se_sys_openat fs/open.c:1370 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1370
 x64_sys_call+0x783/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1578 [inline]
 free_pcp_prepare mm/page_alloc.c:1652 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3618
 free_unref_page+0x95/0x540 mm/page_alloc.c:3716
 free_the_page mm/page_alloc.c:863 [inline]
 __free_pages+0x67/0x100 mm/page_alloc.c:6014
 __vunmap+0x9c0/0xb80 mm/vmalloc.c:2739
 __vfree mm/vmalloc.c:2788 [inline]
 vfree+0x61/0x90 mm/vmalloc.c:2819
 sel_release_policy+0xc2/0xf0 security/selinux/selinuxfs.c:458
 __fput+0x1fc/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88811cc0f100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811cc0f180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88811cc0f200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff88811cc0f280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811cc0f300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
------------[ cut here ]------------
kernel BUG at fs/ext4/extents.c:3190!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 3082 Comm: syz.1.975 Tainted: G    B              syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:ext4_split_extent_at+0xf62/0xf80 fs/ext4/extents.c:3190
Code: ff ff 44 89 f1 80 e1 07 fe c1 38 c1 0f 8c 3f fb ff ff 4c 89 f7 49 89 f7 e8 fb b2 cf ff 4c 89 fe e9 2c fb ff ff e8 de 56 8a ff <0f> 0b e8 d7 56 8a ff 0f 0b e8 d0 56 8a ff 0f 0b e8 c9 56 8a ff 0f
RSP: 0018:ffffc900022d73e0 EFLAGS: 00010293
RAX: ffffffff81e71822 RBX: 0000000000000000 RCX: ffff88812003bcc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000002c
RBP: ffffc900022d7550 R08: 0000000000000000 R09: 0000000050000028
R10: dffffc0000000000 R11: fffffbfff0f6e6fd R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888119164700
FS:  00007f156b8976c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000083 CR3: 0000000114cc0000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ext4_force_split_extent_at fs/ext4/extents.c:338 [inline]
 ext4_ext_remove_space+0x652/0x40d0 fs/ext4/extents.c:2881
 ext4_punch_hole+0x77c/0xbd0 fs/ext4/inode.c:4147
 ext4_fallocate+0x2b6/0x1dc0 fs/ext4/extents.c:4767
 vfs_fallocate+0x4c5/0x5a0 fs/open.c:324
 madvise_remove mm/madvise.c:1049 [inline]
 madvise_vma_behavior mm/madvise.c:1073 [inline]
 madvise_walk_vmas mm/madvise.c:1308 [inline]
 do_madvise+0x1423/0x3290 mm/madvise.c:1487
 __do_sys_madvise mm/madvise.c:1500 [inline]
 __se_sys_madvise mm/madvise.c:1498 [inline]
 __x64_sys_madvise+0xa9/0xc0 mm/madvise.c:1498
 x64_sys_call+0x99e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:29
 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
RIP: 0033:0x7f156a99aef9
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:00007f156b897028 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f156ac05fa0 RCX: 00007f156a99aef9
RDX: 0000000000000009 RSI: 000000000060000b RDI: 0000200000000000
RBP: 00007f156aa2fee0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f156ac06038 R14: 00007f156ac05fa0 R15: 00007ffe4cca9078
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_split_extent_at+0xf62/0xf80 fs/ext4/extents.c:3190
Code: ff ff 44 89 f1 80 e1 07 fe c1 38 c1 0f 8c 3f fb ff ff 4c 89 f7 49 89 f7 e8 fb b2 cf ff 4c 89 fe e9 2c fb ff ff e8 de 56 8a ff <0f> 0b e8 d7 56 8a ff 0f 0b e8 d0 56 8a ff 0f 0b e8 c9 56 8a ff 0f
RSP: 0018:ffffc900022d73e0 EFLAGS: 00010293
RAX: ffffffff81e71822 RBX: 0000000000000000 RCX: ffff88812003bcc0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000002c
RBP: ffffc900022d7550 R08: 0000000000000000 R09: 0000000050000028
R10: dffffc0000000000 R11: fffffbfff0f6e6fd R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888119164700
FS:  00007f156b8976c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000083 CR3: 0000000114cc0000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400