loop2: detected capacity change from 0 to 1024
EXT4-fs: Ignoring removed oldalloc option
EXT4-fs: Ignoring removed orlov option
EXT4-fs (loop2): mounted filesystem without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2602 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x348b/0x40d0 fs/ext4/extents.c:2940
Read of size 4 at addr ffff88812ff73c18 by task syz.2.19/470

CPU: 0 PID: 470 Comm: syz.2.19 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_rm_leaf fs/ext4/extents.c:2602 [inline]
 ext4_ext_remove_space+0x348b/0x40d0 fs/ext4/extents.c:2940
 ext4_ext_truncate+0x200/0x320 fs/ext4/extents.c:4476
 ext4_truncate+0x9be/0xfb0 fs/ext4/inode.c:4297
 ext4_setattr+0x10f1/0x1a60 fs/ext4/inode.c:5651
 notify_change+0xcc3/0xf80 fs/attr.c:499
 do_truncate+0x1ac/0x240 fs/open.c:66
 handle_truncate fs/namei.c:3292 [inline]
 do_open fs/namei.c:3637 [inline]
 path_openat+0x28f0/0x2f80 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_creat fs/open.c:1437 [inline]
 __se_sys_creat fs/open.c:1431 [inline]
 __x64_sys_creat+0x8e/0xb0 fs/open.c:1431
 x64_sys_call+0x116/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:86
 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: 0033:0x7fc973d9acb9
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:00007fc974d01028 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007fc974015fa0 RCX: 00007fc973d9acb9
RDX: 0000000000000000 RSI: 0000000000000108 RDI: 0000200000000680
RBP: 00007fc973e08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc974016038 R14: 00007fc974015fa0 R15: 00007ffcae15a278
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004bfdcc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12ff73
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004bfdcc8 ffffea0004bfdcc8 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:
 ffff88812ff73b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812ff73b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812ff73c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88812ff73c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812ff73d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================