loop0: detected capacity change from 0 to 1024
=======================================================
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:840 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xb61/0xd50 fs/ext4/extents.c:955
Read of size 4 at addr ffff88804d575018 by task syz.0.0/5323

CPU: 0 UID: 0 PID: 5323 Comm: syz.0.0 Not tainted 6.14.0-rc7-syzkaller-00179-gb3ee1e460951 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 ext4_ext_binsearch fs/ext4/extents.c:840 [inline]
 ext4_find_extent+0xb61/0xd50 fs/ext4/extents.c:955
 ext4_ext_map_blocks+0x2e4/0x7d30 fs/ext4/extents.c:4205
 ext4_map_create_blocks fs/ext4/inode.c:516 [inline]
 ext4_map_blocks+0x8bf/0x1990 fs/ext4/inode.c:702
 _ext4_get_block+0x239/0x6b0 fs/ext4/inode.c:781
 ext4_get_block_unwritten+0x2f/0x100 fs/ext4/inode.c:814
 ext4_block_write_begin+0x4d6/0x1510 fs/ext4/inode.c:1063
 ext4_write_begin+0x6c8/0x1280
 ext4_da_write_begin+0x300/0xa60 fs/ext4/inode.c:2925
 generic_perform_write+0x327/0xa00 mm/filemap.c:4102
 ext4_buffered_write_iter+0xc7/0x390 fs/ext4/file.c:299
 ext4_file_write_iter+0x88f/0x1ce0
 new_sync_write fs/read_write.c:586 [inline]
 vfs_write+0xacf/0xd10 fs/read_write.c:679
 ksys_write+0x18f/0x2b0 fs/read_write.c:731
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f41ccf8d169
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:00007f41cddd5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f41cd1a5fa0 RCX: 00007f41ccf8d169
RDX: 000000000000fea7 RSI: 0000200000000180 RDI: 0000000000000007
RBP: 00007f41cd00e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f41cd1a5fa0 R15: 00007ffef3c37448
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4d575
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 dead000000000100 dead000000000122 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:
 ffff88804d574f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804d574f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804d575000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88804d575080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804d575100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================