==================================================================
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 ffff0000e1f27bcc by task syz-executor316/5679

CPU: 0 PID: 5679 Comm: syz-executor316 Not tainted 6.1.141-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:4165
 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
 __block_write_begin_int+0x34c/0x13b8 fs/buffer.c:1991
 __block_write_begin fs/buffer.c:2041 [inline]
 block_page_mkwrite+0x290/0x340 fs/buffer.c:2510
 ext4_page_mkwrite+0x350/0x10a4 fs/ext4/inode.c:6313
 do_page_mkwrite+0x13c/0x358 mm/memory.c:3011
 wp_page_shared+0x148/0x550 mm/memory.c:3360
 do_wp_page+0xca0/0xef0 mm/memory.c:3510
 handle_pte_fault mm/memory.c:5049 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x133c/0x2fd4 mm/memory.c:5294
 __do_page_fault arch/arm64/mm/fault.c:499 [inline]
 do_page_fault+0x310/0x99c arch/arm64/mm/fault.c:583
 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:803
 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:367
 el1h_64_sync_handler+0x80/0xcc arch/arm64/kernel/entry-common.c:427
 el1h_64_sync+0x64/0x68 arch/arm64/kernel/entry.S:580
 __arch_copy_to_user+0x104/0x234 arch/arm64/lib/copy_template.S:135
 do_loop_readv_writev fs/read_write.c:-1 [inline]
 do_iter_read+0x3c0/0x8c4 fs/read_write.c:798
 vfs_readv fs/read_write.c:916 [inline]
 do_preadv+0x1c0/0x2f0 fs/read_write.c:1008
 __do_sys_preadv fs/read_write.c:1058 [inline]
 __se_sys_preadv fs/read_write.c:1053 [inline]
 __arm64_sys_preadv+0xa0/0xb8 fs/read_write.c:1053
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the physical page:
page:000000003946c7d2 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x121f27
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffc0003811608 fffffc000392bc08 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000e1f27a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e1f27b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000e1f27b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff0000e1f27c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000e1f27c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop0): ext4_map_blocks:745: inode #15: block 64424509780: comm syz-executor316: lblock 340 mapped to illegal pblock 64424509780 (length 1)
EXT4-fs error (device loop0): ext4_map_blocks:745: inode #15: block 64424509780: comm syz-executor316: lblock 340 mapped to illegal pblock 64424509780 (length 1)