EXT4-fs error (device loop0): ext4_read_block_bitmap_nowait:476: comm syz-executor.0: Invalid block bitmap block 0 in block_group 0
EXT4-fs (loop0): Remounting filesystem read-only
EXT4-fs error (device loop0) in ext4_mb_clear_bb:5661: Corrupt filesystem
==================================================================
BUG: KASAN: out-of-bounds in ext4_ext_rm_leaf fs/ext4/extents.c:2712 [inline]
BUG: KASAN: out-of-bounds in ext4_ext_remove_space+0x231b/0x4570 fs/ext4/extents.c:2934
Read of size 18446744073709551544 at addr ffff888121ff0054 by task syz-executor.0/339

CPU: 0 PID: 339 Comm: syz-executor.0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0xe2/0x130 mm/kasan/report.c:452
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 ext4_ext_rm_leaf fs/ext4/extents.c:2712 [inline]
 ext4_ext_remove_space+0x231b/0x4570 fs/ext4/extents.c:2934
 ext4_punch_hole+0x6f8/0xad0 fs/ext4/inode.c:4223
 ext4_fallocate+0x271/0x1a70 fs/ext4/extents.c:4764
 vfs_fallocate+0x4b4/0x590 fs/open.c:310
 ioctl_preallocate fs/ioctl.c:494 [inline]
 file_ioctl fs/ioctl.c:537 [inline]
 do_vfs_ioctl+0x11cf/0x14c0 fs/ioctl.c:732
 __do_sys_ioctl fs/ioctl.c:751 [inline]
 __se_sys_ioctl+0x9f/0x1a0 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f5f33316079
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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5f2aac70b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5f33455050 RCX: 00007f5f33316079
RDX: 0000000020000080 RSI: 000000004030582b RDI: 0000000000000004
RBP: 00007f5f33377498 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f5f33455050 R15: 00007fffc90fc328

The buggy address belongs to the page:
page:ffffea000487fc00 refcount:2 mapcount:0 mapping:ffff8881092fcb10 index:0x3a pfn:0x121ff0
aops:def_blk_aops ino:0
flags: 0x4000000000002036(referenced|uptodate|lru|active|private)
raw: 4000000000002036 ffffea00048825c8 ffffea000487b2c8 ffff8881092fcb10
raw: 000000000000003a ffff88811c7dbe70 00000002ffffffff ffff888107ff8000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888107ff8000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 335, ts 38053880623, free_ts 37741606726
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x179/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x223b/0x23d0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x290/0x620 mm/page_alloc.c:5384
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 __page_cache_alloc include/linux/pagemap.h:290 [inline]
 pagecache_get_page+0x63e/0x930 mm/filemap.c:1848
 find_or_create_page include/linux/pagemap.h:402 [inline]
 grow_dev_page fs/buffer.c:976 [inline]
 grow_buffers fs/buffer.c:1045 [inline]
 __getblk_slow fs/buffer.c:1072 [inline]
 __getblk_gfp+0x212/0x780 fs/buffer.c:1370
 sb_getblk_gfp include/linux/buffer_head.h:368 [inline]
 ext4_ext_grow_indepth fs/ext4/extents.c:1327 [inline]
 ext4_ext_create_new_leaf fs/ext4/extents.c:1426 [inline]
 ext4_ext_insert_extent+0x10a2/0x45d0 fs/ext4/extents.c:2098
 ext4_ext_map_blocks+0x17a9/0x5dd0 fs/ext4/extents.c:4362
 ext4_map_blocks+0x985/0x1bd0 fs/ext4/inode.c:674
 _ext4_get_block+0x1d1/0x4e0 fs/ext4/inode.c:817
 ext4_get_block+0x39/0x50 fs/ext4/inode.c:834
 ext4_block_write_begin+0x573/0x1340 fs/ext4/inode.c:1101
 ext4_write_begin+0x67e/0x1690 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x478/0xf10 fs/ext4/inode.c:3033
 generic_perform_write+0x2ce/0x540 mm/filemap.c:3509
 ext4_buffered_write_iter+0x4b8/0x640 fs/ext4/file.c:271
 ext4_file_write_iter+0x53f/0x1980 fs/ext4/file.c:-1
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x129/0x9c0 mm/page_alloc.c:3443
 release_pages+0xe52/0xea0 mm/swap.c:1103
 __pagevec_release+0x71/0xe0 mm/swap.c:1123
 pagevec_release include/linux/pagevec.h:88 [inline]
 truncate_inode_pages_range+0x819/0x16d0 mm/truncate.c:367
 truncate_pagecache_range+0xa1/0xb0 mm/truncate.c:948
 ext4_punch_hole+0x41f/0xad0 fs/ext4/inode.c:4185
 ext4_fallocate+0x271/0x1a70 fs/ext4/extents.c:4764
 vfs_fallocate+0x4b4/0x590 fs/open.c:310
 ioctl_preallocate fs/ioctl.c:494 [inline]
 file_ioctl fs/ioctl.c:537 [inline]
 do_vfs_ioctl+0x11cf/0x14c0 fs/ioctl.c:732
 __do_sys_ioctl fs/ioctl.c:751 [inline]
 __se_sys_ioctl+0x9f/0x1a0 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff888121feff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888121feff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888121ff0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff888121ff0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888121ff0100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop0): __ext4_get_inode_loc:4444: comm syz-executor.0: Invalid inode table block 0 in block_group 0
EXT4-fs error (device loop0) in ext4_reserve_inode_write:5952: Corrupt filesystem
EXT4-fs error (device loop0): ext4_punch_hole:4236: inode #16: comm syz-executor.0: mark_inode_dirty error