==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: slab-out-of-bounds in ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
Read of size 4 at addr ffff88811d27f018 by task kworker/u4:1/10

CPU: 0 PID: 10 Comm: kworker/u4:1 Not tainted 5.15.189-syzkaller-00079-ga71626bd56a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-7:4)
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbeb/0xe20 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x1de/0x6280 fs/ext4/extents.c:4166
 ext4_map_blocks+0x97b/0x1b20 fs/ext4/inode.c:674
 mpage_map_one_extent fs/ext4/inode.c:2421 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline]
 ext4_writepages+0x11e7/0x2f90 fs/ext4/inode.c:2842
 do_writepages+0x48a/0x6c0 mm/page-writeback.c:2388
 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1647
 writeback_sb_inodes+0x9c0/0x1590 fs/fs-writeback.c:1930
 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2106
 wb_do_writeback fs/fs-writeback.c:2253 [inline]
 wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2294
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Allocated by task 101:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 ____kasan_kmalloc mm/kasan/common.c:512 [inline]
 __kasan_kmalloc+0xda/0x110 mm/kasan/common.c:521
 kasan_kmalloc include/linux/kasan.h:227 [inline]
 __kmalloc+0x13d/0x2c0 mm/slub.c:4431
 __kmalloc_node include/linux/slab.h:484 [inline]
 kmalloc_node include/linux/slab.h:639 [inline]
 kvmalloc_node+0x242/0x330 mm/util.c:628
 kvmalloc include/linux/mm.h:851 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x1fc/0xd30 fs/seq_file.c:210
 kernfs_fop_read_iter+0x147/0x470 fs/kernfs/file.c:241
 call_read_iter include/linux/fs.h:2206 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x68b/0xbe0 fs/read_write.c:485
 ksys_read+0x140/0x240 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 x64_sys_call+0x96d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 101:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:365
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
 kasan_slab_free include/linux/kasan.h:193 [inline]
 slab_free_hook mm/slub.c:1723 [inline]
 slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1749
 slab_free mm/slub.c:3521 [inline]
 kfree+0xc4/0x270 mm/slub.c:4583
 kvfree+0x35/0x40 mm/util.c:664
 seq_release+0x57/0x70 fs/seq_file.c:355
 kernfs_fop_release+0x1af/0x250 fs/kernfs/file.c:761
 __fput+0x20b/0x8b0 fs/file_table.c:311
 ____fput+0x15/0x20 fs/file_table.c:339
 task_work_run+0x127/0x190 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0xd0/0xe0 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88811d27e000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 24 bytes to the right of
 4096-byte region [ffff88811d27e000, ffff88811d27f000)
The buggy address belongs to the page:
page:ffffea0004749e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11d278
head:ffffea0004749e00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head|zone=1)
raw: 4000000000010200 0000000000000000 dead000000000122 ffff888100043380
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 101, ts 54249988283, free_ts 53846187885
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5795
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1932 [inline]
 new_slab+0xa1/0x4d0 mm/slub.c:1995
 ___slab_alloc+0x381/0x810 mm/slub.c:3028
 __slab_alloc+0x49/0x90 mm/slub.c:3115
 slab_alloc_node mm/slub.c:3206 [inline]
 slab_alloc mm/slub.c:3250 [inline]
 __kmalloc+0x16a/0x2c0 mm/slub.c:4427
 __kmalloc_node include/linux/slab.h:484 [inline]
 kmalloc_node include/linux/slab.h:639 [inline]
 kvmalloc_node+0x242/0x330 mm/util.c:628
 kvmalloc include/linux/mm.h:851 [inline]
 seq_buf_alloc fs/seq_file.c:38 [inline]
 seq_read_iter+0x1fc/0xd30 fs/seq_file.c:210
 kernfs_fop_read_iter+0x147/0x470 fs/kernfs/file.c:241
 call_read_iter include/linux/fs.h:2206 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x68b/0xbe0 fs/read_write.c:485
 ksys_read+0x140/0x240 fs/read_write.c:623
 __do_sys_read fs/read_write.c:633 [inline]
 __se_sys_read fs/read_write.c:631 [inline]
 __x64_sys_read+0x7b/0x90 fs/read_write.c:631
 x64_sys_call+0x96d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1472 [inline]
 free_pcp_prepare mm/page_alloc.c:1544 [inline]
 free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534
 free_unref_page+0xa2/0x550 mm/page_alloc.c:3616
 free_the_page mm/page_alloc.c:805 [inline]
 __free_pages+0x6c/0x100 mm/page_alloc.c:5871
 __free_slab+0xe8/0x1e0 mm/slub.c:2020
 free_slab mm/slub.c:2035 [inline]
 discard_slab mm/slub.c:2041 [inline]
 __unfreeze_partials+0x160/0x190 mm/slub.c:2527
 put_cpu_partial+0xc6/0x120 mm/slub.c:2607
 __slab_free+0x1d4/0x290 mm/slub.c:3390
 do_slab_free mm/slub.c:3509 [inline]
 ___cache_free+0x104/0x120 mm/slub.c:3530
 qlink_free+0x4d/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x170 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xf0 mm/kasan/common.c:443
 kasan_slab_alloc include/linux/kasan.h:217 [inline]
 slab_post_alloc_hook+0x4f/0x2b0 mm/slab.h:550
 slab_alloc_node mm/slub.c:3240 [inline]
 slab_alloc mm/slub.c:3250 [inline]
 __kmalloc+0x120/0x2c0 mm/slub.c:4427
 kmalloc_array include/linux/slab.h:656 [inline]
 kcalloc include/linux/slab.h:685 [inline]
 iter_file_splice_write+0x17c/0xc30 fs/splice.c:628
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0xe9/0x120 fs/splice.c:936

Memory state around the buggy address:
 ffff88811d27ef00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88811d27ef80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88811d27f000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                            ^
 ffff88811d27f080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88811d27f100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
------------[ cut here ]------------
kernel BUG at fs/ext4/inode.c:2433!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 10 Comm: kworker/u4:1 Tainted: G    B             5.15.189-syzkaller-00079-ga71626bd56a5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-7:4)
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2433 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline]
RIP: 0010:ext4_writepages+0x2eed/0x2f90 fs/ext4/inode.c:2842
Code: 00 74 08 48 89 df e8 22 01 ce ff 48 8b 3b 48 8b 74 24 28 48 8b 54 24 30 44 89 e9 45 89 f0 e8 6a 9b 07 00 eb 51 e8 a3 88 8f ff <0f> 0b e8 9c 88 8f ff eb 2f e8 95 88 8f ff eb 5f e8 8e 88 8f ff 31
RSP: 0018:ffffc900000a7100 EFLAGS: 00010293
RAX: ffffffff81d9272d RBX: ffff888128df6a88 RCX: ffff8881002713c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000a7470 R08: dffffc0000000000 R09: ffffed10251bed4a
R10: ffffed10251bed4a R11: 1ffff110251bed49 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7213370178 CR3: 00000001266c3000 CR4: 00000000003506b0
DR0: 000000000000b2d1 DR1: 0010000000000000 DR2: 0001000000000004
DR3: 0000000000000002 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_writepages+0x48a/0x6c0 mm/page-writeback.c:2388
 __writeback_single_inode+0xd5/0x9c0 fs/fs-writeback.c:1647
 writeback_sb_inodes+0x9c0/0x1590 fs/fs-writeback.c:1930
 wb_writeback+0x3f1/0x980 fs/fs-writeback.c:2106
 wb_do_writeback fs/fs-writeback.c:2253 [inline]
 wb_workfn+0x38f/0xe20 fs/fs-writeback.c:2294
 process_one_work+0x6be/0xba0 kernel/workqueue.c:2325
 worker_thread+0xa59/0x1200 kernel/workqueue.c:2472
 kthread+0x411/0x500 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace fe5a6cbe439990f0 ]---
RIP: 0010:mpage_map_one_extent fs/ext4/inode.c:2433 [inline]
RIP: 0010:mpage_map_and_submit_extent fs/ext4/inode.c:2474 [inline]
RIP: 0010:ext4_writepages+0x2eed/0x2f90 fs/ext4/inode.c:2842
Code: 00 74 08 48 89 df e8 22 01 ce ff 48 8b 3b 48 8b 74 24 28 48 8b 54 24 30 44 89 e9 45 89 f0 e8 6a 9b 07 00 eb 51 e8 a3 88 8f ff <0f> 0b e8 9c 88 8f ff eb 2f e8 95 88 8f ff eb 5f e8 8e 88 8f ff 31
RSP: 0018:ffffc900000a7100 EFLAGS: 00010293
RAX: ffffffff81d9272d RBX: ffff888128df6a88 RCX: ffff8881002713c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900000a7470 R08: dffffc0000000000 R09: ffffed10251bed4a
R10: ffffed10251bed4a R11: 1ffff110251bed49 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5aa0de8ab8 CR3: 00000001188d8000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400