dvmrp0: entered allmulticast mode
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BUG: KASAN: use-after-free in fuse_copy_do+0x193/0x380 fs/fuse/dev.c:-1
Write of size 2 at addr ffff88804bb90fff by task syz.3.888/8933

CPU: 1 UID: 0 PID: 8933 Comm: syz.3.888 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 fuse_copy_do+0x193/0x380 fs/fuse/dev.c:-1
 fuse_copy_folio+0xefc/0x1b00 fs/fuse/dev.c:1166
 fuse_notify_store fs/fuse/dev.c:1821 [inline]
 fuse_notify fs/fuse/dev.c:2109 [inline]
 fuse_dev_do_write+0x2b9d/0x4060 fs/fuse/dev.c:2205
 fuse_dev_write+0x177/0x220 fs/fuse/dev.c:2289
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:688
 ksys_write+0x150/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f59d2f9c799
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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f59d11ee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f59d3215fa0 RCX: 00007f59d2f9c799
RDX: 000000000000002a RSI: 0000200000000080 RDI: 0000000000000008
RBP: 00007f59d3032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f59d3216038 R14: 00007f59d3215fa0 R15: 00007ffefdbc30e8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:3 mapcount:0 mapping:ffff88805d432520 index:0x7 pfn:0x4bb90
memcg:ffff888026701180
aops:empty_aops ino:1 dentry name(?):"/"
flags: 0xfff00000000005(locked|referenced|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000005 0000000000000000 dead000000000122 ffff88805d432520
raw: 0000000000000007 0000000000000000 00000003ffffffff ffff888026701180
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 8933, tgid 8932 (syz.3.888), ts 240352718925, free_ts 240316640055
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1892
 prep_new_page mm/page_alloc.c:1900 [inline]
 get_page_from_freelist+0x23a1/0x2440 mm/page_alloc.c:3965
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5253
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2484
 alloc_frozen_pages_noprof mm/mempolicy.c:2555 [inline]
 alloc_pages_noprof+0xa8/0x190 mm/mempolicy.c:2575
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2585
 filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1013
 __filemap_get_folio_mpol+0x3fc/0xb00 mm/filemap.c:2011
 __filemap_get_folio include/linux/pagemap.h:774 [inline]
 filemap_grab_folio include/linux/pagemap.h:854 [inline]
 fuse_notify_store fs/fuse/dev.c:1813 [inline]
 fuse_notify fs/fuse/dev.c:2109 [inline]
 fuse_dev_do_write+0x298b/0x4060 fs/fuse/dev.c:2205
 fuse_dev_write+0x177/0x220 fs/fuse/dev.c:2289
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61d/0xb90 fs/read_write.c:688
 ksys_write+0x150/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6494 tgid 6494 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1436 [inline]
 free_unref_folios+0xd71/0x1530 mm/page_alloc.c:3043
 folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
 folios_put include/linux/mm.h:1876 [inline]
 folio_batch_move_lru+0x4c2/0x550 mm/swap.c:179
 lru_add_drain_cpu+0xb8/0x7b0 mm/swap.c:654
 lru_add_drain+0x121/0x3e0 mm/swap.c:743
 __folio_batch_release+0x48/0x90 mm/swap.c:1065
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 shmem_undo_range+0x52c/0x1660 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x289/0xae0 mm/shmem.c:1407
 evict+0x61e/0xb10 fs/inode.c:846
 __dentry_kill+0x1a2/0x5e0 fs/dcache.c:670
 finish_dput+0xc9/0x480 fs/dcache.c:879
 end_renaming fs/namei.c:4096 [inline]
 filename_renameat2+0x61e/0x9c0 fs/namei.c:6146
 __do_sys_rename fs/namei.c:6188 [inline]
 __se_sys_rename+0x55/0x2c0 fs/namei.c:6184
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88804bb90f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804bb90f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88804bb91000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88804bb91080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804bb91100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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