EXT4-fs (loop2): mounted filesystem without journal. Opts: errors=remount-ro,dioread_lock,noquota,init_itable,debug,resgid=0x0000000000000000,sysvgroups,discard,usrquota,. Quota mode: writeback.
ext4 filesystem being mounted at /0/file1 supports timestamps until 2038-01-19 (0x7fffffff)
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
Read of size 4 at addr ffff88812e5ba398 by task syz.2.17/371

CPU: 0 PID: 371 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
 ext4_ext_remove_space+0x2bc/0x4180 fs/ext4/extents.c:2834
 ext4_punch_hole+0x77c/0xbd0 fs/ext4/inode.c:4137
 ext4_fallocate+0x2b6/0x1de0 fs/ext4/extents.c:4765
 vfs_fallocate+0x4b4/0x590 fs/open.c:309
 madvise_remove mm/madvise.c:964 [inline]
 madvise_vma_behavior mm/madvise.c:988 [inline]
 madvise_walk_vmas mm/madvise.c:1218 [inline]
 do_madvise+0x12c8/0x2200 mm/madvise.c:1396
 __do_sys_madvise mm/madvise.c:1409 [inline]
 __se_sys_madvise mm/madvise.c:1407 [inline]
 __x64_sys_madvise+0xa9/0xc0 mm/madvise.c:1407
 x64_sys_call+0x89b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:29
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f6ee22b5749
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:00007ffc00e080d8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f6ee250bfa0 RCX: 00007f6ee22b5749
RDX: 0000000000000009 RSI: 0000000000600002 RDI: 0000200000000000
RBP: 00007f6ee2339f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6ee250bfa0 R14: 00007f6ee250bfa0 R15: 0000000000000003
 </TASK>

The buggy address belongs to the page:
page:ffffea0004b96e80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12e5ba
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004b96e88 ffffea0004b96e88 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff88812e5ba280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812e5ba300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812e5ba380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88812e5ba400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812e5ba480: 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:3186!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 371 Comm: syz.2.17 Tainted: G    B             syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:ext4_split_extent_at+0xe5a/0xe80 fs/ext4/extents.c:3186
Code: 6c 76 d3 ff e9 d1 fb ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c de fb ff ff 48 89 df e8 30 76 d3 ff e9 d1 fb ff ff e8 96 f4 94 ff <0f> 0b e8 8f f4 94 ff 0f 0b e8 88 f4 94 ff 0f 0b e8 81 f4 94 ff 0f
RSP: 0018:ffffc90000c074e0 EFLAGS: 00010293
RAX: ffffffff81d3ca4a RBX: 0000000000000000 RCX: ffff888101b9cf00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000002a
RBP: ffffc90000c07650 R08: 0000000000000000 R09: 0000000050000028
R10: fffffbfff0e1824c R11: 1ffffffff0e1824c R12: dffffc0000000000
R13: 000000000000002a R14: 0000000000000030 R15: 0000000000000000
FS:  00005555775a2500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5eebc39000 CR3: 000000012aa9a000 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:319 [inline]
 ext4_ext_remove_space+0x64b/0x4180 fs/ext4/extents.c:2880
 ext4_punch_hole+0x77c/0xbd0 fs/ext4/inode.c:4137
 ext4_fallocate+0x2b6/0x1de0 fs/ext4/extents.c:4765
 vfs_fallocate+0x4b4/0x590 fs/open.c:309
 madvise_remove mm/madvise.c:964 [inline]
 madvise_vma_behavior mm/madvise.c:988 [inline]
 madvise_walk_vmas mm/madvise.c:1218 [inline]
 do_madvise+0x12c8/0x2200 mm/madvise.c:1396
 __do_sys_madvise mm/madvise.c:1409 [inline]
 __se_sys_madvise mm/madvise.c:1407 [inline]
 __x64_sys_madvise+0xa9/0xc0 mm/madvise.c:1407
 x64_sys_call+0x89b/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:29
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f6ee22b5749
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:00007ffc00e080d8 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f6ee250bfa0 RCX: 00007f6ee22b5749
RDX: 0000000000000009 RSI: 0000000000600002 RDI: 0000200000000000
RBP: 00007f6ee2339f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6ee250bfa0 R14: 00007f6ee250bfa0 R15: 0000000000000003
 </TASK>
Modules linked in:
---[ end trace 4630d4914eb39e5a ]---
RIP: 0010:ext4_split_extent_at+0xe5a/0xe80 fs/ext4/extents.c:3186
Code: 6c 76 d3 ff e9 d1 fb ff ff 89 d9 80 e1 07 fe c1 38 c1 0f 8c de fb ff ff 48 89 df e8 30 76 d3 ff e9 d1 fb ff ff e8 96 f4 94 ff <0f> 0b e8 8f f4 94 ff 0f 0b e8 88 f4 94 ff 0f 0b e8 81 f4 94 ff 0f
RSP: 0018:ffffc90000c074e0 EFLAGS: 00010293
RAX: ffffffff81d3ca4a RBX: 0000000000000000 RCX: ffff888101b9cf00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000000002a
RBP: ffffc90000c07650 R08: 0000000000000000 R09: 0000000050000028
R10: fffffbfff0e1824c R11: 1ffffffff0e1824c R12: dffffc0000000000
R13: 000000000000002a R14: 0000000000000030 R15: 0000000000000000
FS:  00005555775a2500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5eebc39000 CR3: 000000012aa9a000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400