syzbot

loop0: detected capacity change from 0 to 128
VFS: Found a Xenix FS (block size = 1024) on device loop0
syz-executor146: attempt to access beyond end of device
loop0: rw=0, sector=6491536, nr_sectors = 2 limit=128
Buffer I/O error on dev loop0, logical block 3245768, async page read
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BUG: KASAN: use-after-free in sysv_new_inode+0xfe4/0x1190 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff8880788651ce by task syz-executor146/5824

CPU: 1 UID: 0 PID: 5824 Comm: syz-executor146 Not tainted 6.14.0-rc2-syzkaller-00390-g224e74511041 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 sysv_new_inode+0xfe4/0x1190 fs/sysv/ialloc.c:153
 sysv_mknod+0x4e/0xe0 fs/sysv/namei.c:53
 vfs_create+0x23c/0x3d0 fs/namei.c:3350
 do_mknodat+0x447/0x5b0 fs/namei.c:4241
 __do_sys_mknodat fs/namei.c:4269 [inline]
 __se_sys_mknodat fs/namei.c:4266 [inline]
 __x64_sys_mknodat+0xa7/0xc0 fs/namei.c:4266
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f64236cb129
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda38d2b68 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f64236cb129
RDX: 0000000000000000 RSI: 0000400000000000 RDI: 00000000ffffff9c
RBP: 00000000ffffffff R08: 0000000000009e8c R09: 0000000000000000
R10: 0000000000000700 R11: 0000000000000246 R12: 0000000000010000
R13: 00007ffda38d2c00 R14: 0000400000000000 R15: 0000000000000003
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7f641b20f pfn:0x78865
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001e771c8 ffffea0001e755c8 0000000000000000
raw: 00000007f641b20f 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5824, tgid 5824 (syz-executor146), ts 62077914485, free_ts 62120425196
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x3651/0x37a0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4739
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 folio_alloc_mpol_noprof mm/mempolicy.c:2289 [inline]
 vma_alloc_folio_noprof+0x12b/0x260 mm/mempolicy.c:2324
 folio_prealloc+0x2e/0x170
 alloc_anon_folio mm/memory.c:4822 [inline]
 do_anonymous_page mm/memory.c:4879 [inline]
 do_pte_missing mm/memory.c:4045 [inline]
 handle_pte_fault mm/memory.c:5889 [inline]
 __handle_mm_fault+0x3e4b/0x70f0 mm/memory.c:6032
 handle_mm_fault+0x2c1/0x7e0 mm/memory.c:6201
 do_user_addr_fault arch/x86/mm/fault.c:1337 [inline]
 handle_page_fault arch/x86/mm/fault.c:1480 [inline]
 exc_page_fault+0x459/0x8b0 arch/x86/mm/fault.c:1538
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
page last free pid 5822 tgid 5822 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_folios+0xe2f/0x18a0 mm/page_alloc.c:2707
 folios_put_refs+0x76c/0x860 mm/swap.c:994
 folios_put include/linux/mm.h:1548 [inline]
 folio_batch_move_lru+0x39a/0x420 mm/swap.c:175
 __folio_batch_add_and_move+0x5bb/0xd70 mm/swap.c:196
 filemap_add_folio+0x24e/0x380 mm/filemap.c:997
 page_cache_ra_unbounded+0x40c/0x820 mm/readahead.c:276
 do_page_cache_ra mm/readahead.c:328 [inline]
 force_page_cache_ra mm/readahead.c:357 [inline]
 page_cache_sync_ra+0x3e2/0xb00 mm/readahead.c:585
 filemap_get_pages+0x59a/0x1fb0 mm/filemap.c:2580
 filemap_read+0x464/0x1260 mm/filemap.c:2691
 blkdev_read_iter+0x31f/0x460 block/fops.c:796
 new_sync_read fs/read_write.c:484 [inline]
 vfs_read+0x975/0xb40 fs/read_write.c:565
 ksys_read+0x18f/0x2b0 fs/read_write.c:708
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888078865080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888078865100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888078865180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff888078865200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888078865280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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