From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f208.google.com (mail-oi1-f208.google.com [209.85.167.208]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2D2F1D130E for ; Sat, 1 Aug 2026 00:00:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.208 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785542437; cv=none; b=qy1NCGoBo/q83nmROMmXQxqM6jcxDt/6LCz6kO7FPx7VwR9Yn8RPMfcmgIiYsf9mivZ1gwHuiERNG7gShUll71KPbNxIfwV8Gzd2MDPyXVghzxBoRPqha7+N5FYsAT90lOermTAh7+OCrfhKj97FBpY6yDd3g7/iuBkGcfLdtnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785542437; c=relaxed/simple; bh=J8cLEEt3aKwvbcWpn8eov2BtA/Yx0lmYpzMPQuWuJLE=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6808:c191:b0:495:e92e:d797 with SMTP id 5614622812f47-4af5e1d395fmr3683836b6e.11.1785542433977; Fri, 31 Jul 2026 17:00:33 -0700 (PDT) Date: Fri, 31 Jul 2026 17:00:33 -0700 In-Reply-To: <6a6aac38.79190830.3d7c75.0018.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a6d3721.13bfb6d0.1ecdd5.0250.GAE@google.com> Subject: Re: [syzbot] [fs?] KASAN: slab-use-after-free Read in lookup_noperm_common From: syzbot To: andi.shyti@kernel.org, dakr@kernel.org, driver-core@lists.linux.dev, gregkh@linuxfoundation.org, hdanton@sina.com, johan@kernel.org, linux-fsdevel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, rafael@kernel.org, syzkaller-bugs@googlegroups.com, vasilisalmpanis@gmail.com, wsa@sang-engineering.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: cc2b5f627e8c Add linux-next specific files for 20260714 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=10d94e32580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f dashboard link: https://syzkaller.appspot.com/bug?extid=23ad911c819b923238b7 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=12f3a5b9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12ac4c9e580000 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+23ad911c819b923238b7@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in lookup_noperm_common+0x407/0x430 fs/namei.c:3106 Read of size 4 at addr ffff888040cd8000 by task syz-executor329/6384 CPU: 0 UID: 0 PID: 6384 Comm: syz-executor329 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 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 lookup_noperm_common+0x407/0x430 fs/namei.c:3106 simple_start_creating+0x9c/0x110 fs/libfs.c:2302 debugfs_start_creating+0xdb/0x1a0 fs/debugfs/inode.c:394 debugfs_create_dir+0x24/0x350 fs/debugfs/inode.c:572 i2c_device_probe+0x814/0xbf0 drivers/i2c/i2c-core-base.c:588 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c7/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12d/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3772 i2c_new_client_device+0xa29/0x1130 drivers/i2c/i2c-core-base.c:1019 new_device_store+0x24b/0x530 drivers/i2c/i2c-core-base.c:1307 kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x61e/0xbb0 fs/read_write.c:687 ksys_write+0x156/0x270 fs/read_write.c:739 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: 0033:0x7f8c042ca209 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 d0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8c03a89128 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f8c04370908 RCX: 00007f8c042ca209 RDX: 000000000000000f RSI: 0000200000000700 RDI: 0000000000000004 RBP: 00007f8c04370900 R08: 00007f8c03a89cdc R09: 0000000000000000 R10: 00007f8c03a89cdc R11: 0000000000000246 R12: 00007f8c0437090c R13: 000000000000000b R14: 00007ffca85726b0 R15: 00007ffca8572798 Allocated by task 44: 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_lru_noprof+0x355/0x670 mm/slub.c:4954 __d_alloc+0x37/0x6f0 fs/dcache.c:1902 d_alloc+0x4b/0x190 fs/dcache.c:1981 lookup_one_qstr_excl+0xd8/0x360 fs/namei.c:1806 __start_dirop fs/namei.c:2920 [inline] start_dirop+0x5c/0x90 fs/namei.c:2942 simple_start_creating+0xcc/0x110 fs/libfs.c:2305 debugfs_start_creating+0xdb/0x1a0 fs/debugfs/inode.c:394 debugfs_create_dir+0x24/0x350 fs/debugfs/inode.c:572 i2c_register_adapter+0xc14/0x1400 drivers/i2c/i2c-core-base.c:1609 dvb_usb_i2c_init+0x1fc/0x2e0 drivers/media/usb/dvb-usb/dvb-usb-i2c.c:31 dvb_usb_init drivers/media/usb/dvb-usb/dvb-usb-init.c:183 [inline] dvb_usb_device_init+0xf30/0x2570 drivers/media/usb/dvb-usb/dvb-usb-init.c:310 dibusb_probe+0xb7/0xf0 drivers/media/usb/dvb-usb/dibusb-mb.c:116 usb_probe_interface+0x788/0xe50 drivers/usb/core/driver.c:399 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c7/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12d/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3772 usb_set_configuration+0x1ad8/0x2180 drivers/usb/core/message.c:2268 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x254/0xae0 drivers/base/dd.c:706 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868 driver_probe_device+0x4f/0x240 drivers/base/dd.c:898 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1026 bus_for_each_drv+0x25b/0x2f0 drivers/base/bus.c:500 __device_attach+0x2c7/0x450 drivers/base/dd.c:1098 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x12d/0x220 drivers/base/bus.c:620 device_add+0x7d7/0xb80 drivers/base/core.c:3772 usb_new_device+0x98d/0x1610 drivers/usb/core/hub.c:2695 hub_port_connect drivers/usb/core/hub.c:5567 [inline] hub_port_connect_change drivers/usb/core/hub.c:5707 [inline] port_event drivers/usb/core/hub.c:5871 [inline] hub_event+0x28cf/0x4cf0 drivers/usb/core/hub.c:5953 process_one_work+0xaaf/0x1480 kernel/workqueue.c:3379 process_scheduled_works kernel/workqueue.c:3462 [inline] worker_thread+0xb05/0x10d0 kernel/workqueue.c:3543 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 29: 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 rcu_do_batch kernel/rcu/tree.c:2645 [inline] rcu_core kernel/rcu/tree.c:2897 [inline] rcu_cpu_kthread+0x950/0x1480 kernel/rcu/tree.c:2985 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Last potentially related work creation: kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556 __call_rcu_common kernel/rcu/tree.c:3159 [inline] call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3279 dentry_kill+0x4d3/0x880 fs/dcache.c:845 finish_dput+0x1a/0x260 fs/dcache.c:1001 debugfs_remove+0x5b/0x70 fs/debugfs/inode.c:781 i2c_del_adapter+0x229/0x430 drivers/i2c/i2c-core-base.c:1829 dvb_usb_i2c_exit+0x64/0xb0 drivers/media/usb/dvb-usb/dvb-usb-i2c.c:46 dvb_usb_exit drivers/media/usb/dvb-usb/dvb-usb-init.c:144 [inline] dvb_usb_device_exit+0x1cb/0x350 drivers/media/usb/dvb-usb/dvb-usb-init.c:338 usb_unbind_interface+0x295/0x9f0 drivers/usb/core/driver.c:461 device_remove drivers/base/dd.c:618 [inline] __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x4f5/0x880 drivers/base/dd.c:1372 bus_remove_device+0x449/0x560 drivers/base/bus.c:664 device_del+0x528/0x8f0 drivers/base/core.c:3961 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1478 usb_disconnect+0x32d/0x990 drivers/usb/core/hub.c:2345 hub_port_connect drivers/usb/core/hub.c:5407 [inline] hub_port_connect_change drivers/usb/core/hub.c:5707 [inline] port_event drivers/usb/core/hub.c:5871 [inline] hub_event+0x1bb7/0x4cf0 drivers/usb/core/hub.c:5953 process_one_work+0xaaf/0x1480 kernel/workqueue.c:3379 process_scheduled_works kernel/workqueue.c:3462 [inline] worker_thread+0xb05/0x10d0 kernel/workqueue.c:3543 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 The buggy address belongs to the object at ffff888040cd8000 which belongs to the cache dentry of size 376 The buggy address is located 0 bytes inside of freed 376-byte region [ffff888040cd8000, ffff888040cd8178) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888040cd9b80 pfn:0x40cd8 head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:ffff8880276f0201 flags: 0x80000000000240(workingset|head|node=0|zone=1) page_type: f5(slab) raw: 0080000000000240 ffff88801c2f6500 ffffea00011add10 ffffea00013fbf10 raw: ffff888040cd9b80 0000000800120011 00000000f5000000 ffff8880276f0201 head: 0080000000000240 ffff88801c2f6500 ffffea00011add10 ffffea00013fbf10 head: ffff888040cd9b80 0000000800120011 00000000f5000000 ffff8880276f0201 head: 0080000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 1, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4962, tgid 4962 (udevd), ts 59068459425 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_lru_noprof+0x44d/0x670 mm/slub.c:4954 __d_alloc+0x37/0x6f0 fs/dcache.c:1902 d_alloc+0x4b/0x190 fs/dcache.c:1981 lookup_one_qstr_excl+0xd8/0x360 fs/namei.c:1806 __start_renaming+0x1da/0x410 fs/namei.c:3888 filename_renameat2+0x3a0/0x9b0 fs/namei.c:6161 __do_sys_rename fs/namei.c:6230 [inline] __se_sys_rename+0x55/0x2c0 fs/namei.c:6226 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 page_owner free stack trace missing Memory state around the buggy address: ffff888040cd7f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888040cd7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888040cd8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888040cd8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888040cd8100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc ================================================================== --- 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.