==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0x994/0xb6c fs/ext4/extents.c:953
Read of size 4 at addr ffff0000e27aec98 by task syz.2.296/6860

CPU: 0 PID: 6860 Comm: syz.2.296 Not tainted 6.1.145-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 print_address_description+0x88/0x220 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:427
 kasan_report+0xa8/0x100 mm/kasan/report.c:531
 __asan_report_load4_noabort+0x2c/0x38 mm/kasan/report_generic.c:350
 ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0x994/0xb6c fs/ext4/extents.c:953
 ext4_ext_map_blocks+0x240/0x559c fs/ext4/extents.c:4166
 ext4_map_blocks+0x860/0x1770 fs/ext4/inode.c:679
 _ext4_get_block+0x194/0x4c8 fs/ext4/inode.c:822
 ext4_get_block_unwritten+0x3c/0x114 fs/ext4/inode.c:855
 ext4_block_write_begin+0x508/0x10f8 fs/ext4/inode.c:1124
 ext4_write_begin+0x5ec/0x133c fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x360/0x9d8 fs/ext4/inode.c:3000
 generic_perform_write+0x230/0x4b0 mm/filemap.c:3846
 ext4_buffered_write_iter+0x2c4/0x530 fs/ext4/file.c:285
 ext4_file_write_iter+0x188/0x152c fs/ext4/file.c:-1
 __kernel_write_iter+0x200/0x558 fs/read_write.c:517
 dump_emit_page fs/coredump.c:950 [inline]
 dump_user_range+0x318/0x5e8 fs/coredump.c:977
 elf_core_dump+0x27bc/0x2cc4 fs/binfmt_elf.c:2354
 do_coredump+0x10c4/0x1c4c fs/coredump.c:824
 get_signal+0xdec/0x1310 kernel/signal.c:2857
 do_signal arch/arm64/kernel/signal.c:1081 [inline]
 do_notify_resume+0x290/0x2b0c arch/arm64/kernel/signal.c:1134
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
 el0_da+0xb4/0x154 arch/arm64/kernel/entry-common.c:516
 el0t_64_sync_handler+0x90/0xf0 arch/arm64/kernel/entry-common.c:658
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the physical page:
page:00000000bd5eb8c6 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1227ae
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000e27aeb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e27aec00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000e27aec80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff0000e27aed00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e27aed80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop2): ext4_ext_split:1080: inode #18: comm syz.2.296: p_ext > EXT_MAX_EXTENT!
EXT4-fs (loop2): unmounting filesystem.