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X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69a75f9b.a70a0220.b118c.0013.GAE@google.com> Subject: [syzbot] [fuse?] KASAN: use-after-free Write in fuse_copy_do From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: c025f6cf4209 Add linux-next specific files for 20260303 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=135770ba580000 kernel config: https://syzkaller.appspot.com/x/.config?x=54b410fabe2a4318 dashboard link: https://syzkaller.appspot.com/bug?extid=23299dfcac137a96834a compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1671b006580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1166bb5a580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/e2497bde352d/disk-c025f6cf.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/36827cb45429/vmlinux-c025f6cf.xz kernel image: https://storage.googleapis.com/syzbot-assets/7ebf1ed6bb73/bzImage-c025f6cf.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+23299dfcac137a96834a@syzkaller.appspotmail.com ================================================================== BUG: KASAN: use-after-free in fuse_copy_do+0x193/0x380 fs/fuse/dev.c:-1 Write of size 2 at addr ffff888070528fff by task syz.0.17/6005 CPU: 0 UID: 0 PID: 6005 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: 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: 0033:0x7fe8c659c799 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:00007fe8c7476028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe8c6815fa0 RCX: 00007fe8c659c799 RDX: 000000000000002a RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007fe8c6632bd9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe8c6816038 R14: 00007fe8c6815fa0 R15: 00007ffd95eaba38 The buggy address belongs to the physical page: page: refcount:3 mapcount:0 mapping:ffff88805c1c4f20 index:0x7 pfn:0x70528 memcg:ffff88802ce3a880 aops:empty_aops ino:1 dentry name(?):"/" flags: 0xfff00000000005(locked|referenced|node=0|zone=1|lastcpupid=0x7ff) raw: 00fff00000000005 0000000000000000 dead000000000122 ffff88805c1c4f20 raw: 0000000000000007 0000000000000000 00000003ffffffff ffff88802ce3a880 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 6005, tgid 6004 (syz.0.17), ts 103948279019, free_ts 103868818778 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 6002 tgid 6002 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 free_pages_and_swap_cache+0x2e7/0x5b0 mm/swap_state.c:401 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline] tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:424 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:549 exit_mmap+0x498/0xa10 mm/mmap.c:1315 __mmput+0x118/0x430 kernel/fork.c:1179 exit_mm+0x18e/0x250 kernel/exit.c:581 do_exit+0x8b9/0x2580 kernel/exit.c:962 do_group_exit+0x21b/0x2d0 kernel/exit.c:1116 __do_sys_exit_group kernel/exit.c:1127 [inline] __se_sys_exit_group kernel/exit.c:1125 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1125 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232 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: ffff888070528f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888070528f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff888070529000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff888070529080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff888070529100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ================================================================== --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup