sysv_free_block: flc_count > flc_size
sysv_free_block: flc_count > flc_size
sysv_free_block: flc_count > flc_size
==================================================================
BUG: KASAN: use-after-free in sysv_new_block+0x7a7/0xa50 fs/sysv/balloc.c:113
Read of size 4 at addr ffff88803f28a0c8 by task syz-executor.0/5542

CPU: 1 UID: 0 PID: 5542 Comm: syz-executor.0 Not tainted 6.11.0-rc5-syzkaller-g20371ba12063 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xc3/0x620 mm/kasan/report.c:488
 kasan_report+0xd9/0x110 mm/kasan/report.c:601
 sysv_new_block+0x7a7/0xa50 fs/sysv/balloc.c:113
 alloc_branch fs/sysv/itree.c:135 [inline]
 get_block+0x261/0x1570 fs/sysv/itree.c:254
 __block_write_begin_int+0x4fb/0x16e0 fs/buffer.c:2125
 __block_write_begin fs/buffer.c:2174 [inline]
 block_write_begin+0xb1/0x4a0 fs/buffer.c:2235
 sysv_write_begin+0x31/0xe0 fs/sysv/itree.c:490
 generic_perform_write+0x312/0xaa0 mm/filemap.c:4019
 __generic_file_write_iter+0x1fd/0x240 mm/filemap.c:4121
 generic_file_write_iter+0xe7/0x350 mm/filemap.c:4147
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0x6b6/0x1140 fs/read_write.c:590
 ksys_write+0x12f/0x260 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1025c7dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f10269280c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1025dabf80 RCX: 00007f1025c7dda9
RDX: 00000000fffffe45 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 00007f1025cca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f1025dabf80 R15: 00007ffc9e676e38
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x5850 pfn:0x3f28a
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000005850 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x152c4a(GFP_NOFS|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 5358, tgid 5358 (syz-executor), ts 71736410869, free_ts 91515350253
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1493
 prep_new_page mm/page_alloc.c:1501 [inline]
 get_page_from_freelist+0x1351/0x2e50 mm/page_alloc.c:3439
 __alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4695
 alloc_pages_mpol_noprof+0x275/0x610 mm/mempolicy.c:2263
 folio_alloc_noprof+0x1e/0xc0 mm/mempolicy.c:2350
 filemap_alloc_folio_noprof+0x3ba/0x490 mm/filemap.c:1008
 page_cache_ra_unbounded+0x1c8/0x5a0 mm/readahead.c:248
 do_page_cache_ra mm/readahead.c:303 [inline]
 page_cache_ra_order+0x6b5/0xb80 mm/readahead.c:488
 page_cache_async_ra+0x5cb/0x820 mm/readahead.c:638
 filemap_readahead mm/filemap.c:2504 [inline]
 filemap_get_pages+0x357/0x1830 mm/filemap.c:2545
 filemap_read+0x3af/0xd10 mm/filemap.c:2625
 generic_file_read_iter+0x350/0x460 mm/filemap.c:2806
 ext4_file_read_iter+0x1dc/0x6c0 fs/ext4/file.c:147
 __kernel_read+0x3ec/0xb50 fs/read_write.c:434
 integrity_kernel_read+0x7f/0xb0 security/integrity/iint.c:28
 ima_calc_file_hash_tfm+0x2cf/0x3e0 security/integrity/ima/ima_crypto.c:480
page last free pid 5473 tgid 5473 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1094 [inline]
 free_unref_folios+0x9e9/0x1390 mm/page_alloc.c:2660
 folios_put_refs+0x560/0x760 mm/swap.c:1039
 folio_batch_release include/linux/pagevec.h:101 [inline]
 truncate_inode_pages_range+0x334/0xe80 mm/truncate.c:346
 ext4_evict_inode+0x2cc/0x17d0 fs/ext4/inode.c:193
 evict+0x398/0x8c0 fs/inode.c:704
 iput_final fs/inode.c:1838 [inline]
 iput.part.0+0x5a8/0x7f0 fs/inode.c:1864
 iput+0x5c/0x80 fs/inode.c:1854
 do_unlinkat+0x613/0x750 fs/namei.c:4493
 __do_sys_unlink fs/namei.c:4534 [inline]
 __se_sys_unlink fs/namei.c:4532 [inline]
 __x64_sys_unlink+0xc5/0x110 fs/namei.c:4532
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803f289f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803f28a000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803f28a080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff88803f28a100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803f28a180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================