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2002:a05:6808:1446:b0:495:feaa:9e39 with SMTP id 5614622812f47-4ad5b942f71mr1474809b6e.6.1785248138541; Tue, 28 Jul 2026 07:15:38 -0700 (PDT) Date: Tue, 28 Jul 2026 07:15:38 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a68b98a.4c659fcc.19cd90.0026.GAE@google.com> Subject: [syzbot] [fs?] KASAN: slab-use-after-free Read in configfs_dirent_is_ready From: syzbot To: a.hindborg@kernel.org, leitao@debian.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: cc2b5f627e8c Add linux-next specific files for 20260714 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=134ee6b9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f dashboard link: https://syzkaller.appspot.com/bug?extid=8358d1f3d9c15bdf1c9a compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=138ec6b9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10e27746580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6836f8efb1da/disk-cc2b5f62.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0109d3477cc7/vmlinux-cc2b5f62.xz kernel image: https://storage.googleapis.com/syzbot-assets/c2e49e350bbf/bzImage-cc2b5f62.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+8358d1f3d9c15bdf1c9a@syzkaller.appspotmail.com Mass Storage Function, version: 2009/09/11 LUN: removable file: (no medium) ================================================================== BUG: KASAN: slab-use-after-free in configfs_dirent_is_ready+0x6d/0x70 fs/configfs/dir.c:363 Read of size 4 at addr ffff888042fc4038 by task syz.3.78/6037 CPU: 0 UID: 0 PID: 6037 Comm: syz.3.78 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 configfs_dirent_is_ready+0x6d/0x70 fs/configfs/dir.c:363 create_link fs/configfs/symlink.c:85 [inline] configfs_symlink+0x616/0x1030 fs/configfs/symlink.c:199 vfs_symlink+0x18b/0x330 fs/namei.c:5654 filename_symlinkat+0x1cd/0x420 fs/namei.c:5679 __do_sys_symlinkat fs/namei.c:5699 [inline] __se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5694 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f6fdb4cde99 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:00007ffcf02e68f8 EFLAGS: 00000246 ORIG_RAX: 000000000000010a RAX: ffffffffffffffda RBX: 00007f6fdb755fa0 RCX: 00007f6fdb4cde99 RDX: 0000200000000300 RSI: ffffffffffffff9c RDI: 0000200000000200 RBP: 00007f6fdb563eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6fdb755fac R14: 00007f6fdb755fa0 R15: 00007f6fdb755fa0 Allocated by task 6037: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4608 [inline] slab_alloc_node mm/slub.c:4921 [inline] kmem_cache_alloc_noprof+0x358/0x680 mm/slub.c:4935 configfs_new_dirent+0x59/0x470 fs/configfs/dir.c:193 configfs_make_dirent fs/configfs/dir.c:259 [inline] configfs_create_dir fs/configfs/dir.c:304 [inline] configfs_attach_item+0xa1/0xd60 fs/configfs/dir.c:863 configfs_attach_group+0x2a/0x370 fs/configfs/dir.c:898 configfs_mkdir+0x6f0/0x9e0 fs/configfs/dir.c:1423 vfs_mkdir+0x408/0x620 fs/namei.c:5270 filename_mkdirat+0x289/0x520 fs/namei.c:5303 __do_sys_mkdirat fs/namei.c:5324 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5321 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 6036: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2706 [inline] slab_free mm/slub.c:6388 [inline] kmem_cache_free+0x187/0x6c0 mm/slub.c:6515 release_configfs_dirent fs/configfs/configfs_internal.h:139 [inline] configfs_put fs/configfs/configfs_internal.h:156 [inline] configfs_d_iput+0x209/0x270 fs/configfs/dir.c:63 d_delete_notify include/linux/fsnotify.h:379 [inline] vfs_rmdir+0x24a/0x6b0 fs/namei.c:5388 filename_rmdir+0x292/0x520 fs/namei.c:5432 __do_sys_rmdir fs/namei.c:5455 [inline] __se_sys_rmdir+0x2e/0x140 fs/namei.c:5452 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff888042fc4000 which belongs to the cache configfs_dir_cache of size 96 The buggy address is located 56 bytes inside of freed 96-byte region [ffff888042fc4000, ffff888042fc4060) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x42fc4 flags: 0x80000000000000(node=0|zone=1) page_type: f5(slab) raw: 0080000000000000 ffff88801f69f780 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800200020 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6024, tgid 6024 (syz.1.68), ts 137140557127 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x264c/0x26c0 mm/page_alloc.c:3955 __alloc_frozen_pages_noprof+0x222/0x5b0 mm/page_alloc.c:5394 alloc_slab_page mm/slub.c:3295 [inline] allocate_slab+0x7c/0x5e0 mm/slub.c:3410 new_slab mm/slub.c:3456 [inline] refill_objects+0x2d8/0x350 mm/slub.c:7321 refill_sheaf mm/slub.c:2833 [inline] __pcs_replace_empty_main+0x330/0x690 mm/slub.c:4699 alloc_from_pcs mm/slub.c:4775 [inline] slab_alloc_node mm/slub.c:4909 [inline] kmem_cache_alloc_noprof+0x455/0x680 mm/slub.c:4935 configfs_new_dirent+0x59/0x470 fs/configfs/dir.c:193 configfs_make_dirent+0x35/0x160 fs/configfs/dir.c:259 configfs_create_file+0xe3/0x130 fs/configfs/file.c:454 populate_attrs fs/configfs/dir.c:640 [inline] configfs_attach_item+0x8df/0xd60 fs/configfs/dir.c:865 configfs_attach_group+0x2a/0x370 fs/configfs/dir.c:898 create_default_group+0x87/0x180 fs/configfs/dir.c:720 populate_groups fs/configfs/dir.c:741 [inline] configfs_attach_group+0x169/0x370 fs/configfs/dir.c:914 configfs_mkdir+0x6f0/0x9e0 fs/configfs/dir.c:1423 vfs_mkdir+0x408/0x620 fs/namei.c:5270 page last free pid 5732 tgid 5732 ts 137112389589 stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] __free_frozen_pages+0x1185/0x1270 mm/page_alloc.c:2962 ___free_pages_bulk mm/kasan/shadow.c:333 [inline] __kasan_populate_vmalloc_do mm/kasan/shadow.c:385 [inline] __kasan_populate_vmalloc+0x12d/0x1c0 mm/kasan/shadow.c:424 kasan_populate_vmalloc include/linux/kasan.h:580 [inline] alloc_vmap_area+0xd1a/0x1420 mm/vmalloc.c:2176 __get_vm_area_node+0x1f2/0x300 mm/vmalloc.c:3279 __vmalloc_node_range_noprof+0x34e/0x1560 mm/vmalloc.c:4211 __vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4312 alloc_thread_stack_node kernel/fork.c:359 [inline] dup_task_struct+0x2a0/0x8e0 kernel/fork.c:929 copy_process+0x820/0x43f0 kernel/fork.c:2132 kernel_clone+0x2d7/0x940 kernel/fork.c:2765 __do_sys_clone kernel/fork.c:2907 [inline] __se_sys_clone kernel/fork.c:2891 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2891 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff888042fc3f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff888042fc3f80: 00 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc >ffff888042fc4000: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ^ ffff888042fc4080: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ffff888042fc4100: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc ================================================================== --- This report is generated by a bot. 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