==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
Read of size 4 at addr ffff88811d67bc94 by task kworker/u4:1/10

CPU: 0 PID: 10 Comm: kworker/u4:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: writeback wb_workfn (flush-7:2)
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 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_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:953
 ext4_ext_map_blocks+0x1da/0x6080 fs/ext4/extents.c:4166
 ext4_map_blocks+0x9cb/0x1b60 fs/ext4/inode.c:679
 mpage_map_one_extent fs/ext4/inode.c:2435 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2488 [inline]
 ext4_writepages+0x1260/0x3020 fs/ext4/inode.c:2856
 do_writepages+0x3a9/0x5e0 mm/page-writeback.c:2494
 __writeback_single_inode+0xc6/0xad0 fs/fs-writeback.c:1612
 writeback_sb_inodes+0x9b8/0x1550 fs/fs-writeback.c:1903
 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2079
 wb_do_writeback fs/fs-writeback.c:2226 [inline]
 wb_workfn+0x350/0xda0 fs/fs-writeback.c:2266
 process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
 worker_thread+0xa29/0x11f0 kernel/workqueue.c:2449
 kthread+0x281/0x320 kernel/kthread.c:386
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 132:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:52
 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:333
 kasan_slab_alloc include/linux/kasan.h:202 [inline]
 slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
 slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc+0x16e/0x330 mm/slub.c:3408
 vm_area_alloc+0x24/0x1a0 kernel/fork.c:496
 __mmap_region mm/mmap.c:2860 [inline]
 mmap_region+0xf9f/0x2290 mm/mmap.c:3028
 do_mmap+0x843/0xdc0 mm/mmap.c:1490
 vm_mmap_pgoff+0x1f5/0x3f0 mm/util.c:525
 ksys_mmap_pgoff+0x161/0x1d0 mm/mmap.c:1536
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:93 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
 __x64_sys_mmap+0xfa/0x110 arch/x86/kernel/sys_x86_64.c:86
 x64_sys_call+0x8fd/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff88811d67bc60
 which belongs to the cache vm_area_struct of size 200
The buggy address is located 52 bytes inside of
 200-byte region [ffff88811d67bc60, ffff88811d67bd28)

The buggy address belongs to the physical page:
page:ffffea0004759ec0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88811d67be70 pfn:0x11d67b
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 ffffea0004759f48 ffffea0004759e48 ffff8881001eaa80
raw: ffff88811d67be70 00000000000f0006 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 132, tgid 132 (sh), ts 7738171582, free_ts 0
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650
 get_page_from_freelist+0x2c7b/0x2cf0 mm/page_alloc.c:4554
 __alloc_pages+0x1c3/0x450 mm/page_alloc.c:5868
 alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
 allocate_slab mm/slub.c:1967 [inline]
 new_slab+0x98/0x3d0 mm/slub.c:2020
 ___slab_alloc+0x6bd/0xb20 mm/slub.c:3177
 __slab_alloc+0x5e/0xa0 mm/slub.c:3263
 slab_alloc_node mm/slub.c:3348 [inline]
 slab_alloc mm/slub.c:3392 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3399 [inline]
 kmem_cache_alloc+0x1b0/0x330 mm/slub.c:3408
 vm_area_dup+0x27/0x280 kernel/fork.c:511
 __split_vma+0x1d2/0x930 mm/mmap.c:2439
 do_mas_align_munmap+0x2e1/0x1230 mm/mmap.c:2565
 do_mas_munmap+0x241/0x2b0 mm/mmap.c:2749
 __mmap_region mm/mmap.c:2797 [inline]
 mmap_region+0x6b4/0x2290 mm/mmap.c:3028
 do_mmap+0x843/0xdc0 mm/mmap.c:1490
 vm_mmap_pgoff+0x1f5/0x3f0 mm/util.c:525
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88811d67bb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d67bc00: fb fb fb fb fc fc fc fc fc fc fc fc fb fb fb fb
>ffff88811d67bc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff88811d67bd00: fb fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb
 ffff88811d67bd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
EXT4-fs warning (device loop2): ext4_convert_unwritten_extents:4872: inode #15: block 36: len 1: ext4_ext_map_blocks returned -28