From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f78.google.com (mail-oo1-f78.google.com [209.85.161.78]) (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 EE16333D4E4 for ; Thu, 19 Mar 2026 07:21:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.78 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773904897; cv=none; b=S68HoUPVvg+VbcnnLXOIaoXW5Exz6szpwaJyHI+92cHo2IPqRBUK17E1RsftbFK7RIgg81DU9X74wFVsGwXx6kXA/r/c5ChB3U6fOl/T/gNDu6TryDJUnWIepJPsHN5VU/uwmH7J/BnMWZ2B1MuLH70GW9/eRGF5IRdDnQnUK7Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773904897; c=relaxed/simple; bh=+6YOSkAia3MK4Mq1F9YvlW2Ab67ia1hUEvE1KVhEuJ0=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; 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006d021491bc7-67c0daf21f6mr4895329eaf.37.1773904894957; Thu, 19 Mar 2026 00:21:34 -0700 (PDT) Date: Thu, 19 Mar 2026 00:21:34 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69bba3fe.050a0220.227207.0030.GAE@google.com> Subject: [syzbot] [media?] [usb?] KASAN: slab-use-after-free Read in v4l2_open From: syzbot To: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-usb@vger.kernel.org, mchehab@kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 8e5a478b6d6a Add linux-next specific files for 20260317 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=1197006a580000 kernel config: https://syzkaller.appspot.com/x/.config?x=6f3ef9419150a4b1 dashboard link: https://syzkaller.appspot.com/bug?extid=1a7507a194fff09e5c44 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=1161bd52580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16bfc216580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/4fb0843c2e97/disk-8e5a478b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/59d50c6221b4/vmlinux-8e5a478b.xz kernel image: https://storage.googleapis.com/syzbot-assets/891eb3906306/bzImage-8e5a478b.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+1a7507a194fff09e5c44@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 Read of size 4 at addr ffff88801b168810 by task v4l_id/6152 CPU: 1 UID: 0 PID: 6152 Comm: v4l_id 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+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 v4l2_open+0x395/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:444 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411 do_dentry_open+0x785/0x14e0 fs/open.c:949 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4693 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4852 do_file_open+0x23e/0x4a0 fs/namei.c:4881 do_sys_openat2+0x113/0x200 fs/open.c:1366 do_sys_open fs/open.c:1372 [inline] __do_sys_openat fs/open.c:1388 [inline] __se_sys_openat fs/open.c:1383 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1383 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: 0033:0x7fa818fde407 Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff RSP: 002b:00007ffdbeaca3e0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007fa818f52880 RCX: 00007fa818fde407 RDX: 0000000000000000 RSI: 00007ffdbeacaf1c RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffdbeaca630 R14: 00007fa819237000 R15: 0000562990aec4d8 Allocated by task 809: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5412 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] em28xx_v4l2_init+0x10b/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2538 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117 process_one_work+0x9ab/0x1780 kernel/workqueue.c:3289 process_scheduled_works kernel/workqueue.c:3380 [inline] worker_thread+0xba8/0x11e0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 809: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 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:2689 [inline] slab_free mm/slub.c:6242 [inline] kfree+0x1c5/0x650 mm/slub.c:6557 em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline] kref_put include/linux/kref.h:65 [inline] em28xx_v4l2_init+0x1683/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2907 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117 process_one_work+0x9ab/0x1780 kernel/workqueue.c:3289 process_scheduled_works kernel/workqueue.c:3380 [inline] worker_thread+0xba8/0x11e0 kernel/workqueue.c:3466 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 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 ffff88801b168000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2064 bytes inside of freed 8192-byte region [ffff88801b168000, ffff88801b16a000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b168 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801b042280 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801b042280 dead000000000100 dead000000000122 head: 0000000000000000 0000000800020002 00000000f5000000 0000000000000000 head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5499, tgid 5499 (S40network), ts 54008512816, free_ts 53918866034 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x231/0x280 mm/page_alloc.c:1857 prep_new_page mm/page_alloc.c:1865 [inline] get_page_from_freelist+0x2418/0x24b0 mm/page_alloc.c:3924 __alloc_frozen_pages_noprof+0x233/0x3d0 mm/page_alloc.c:5211 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7247 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4651 alloc_from_pcs mm/slub.c:4749 [inline] slab_alloc_node mm/slub.c:4883 [inline] __kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5407 kmalloc_noprof include/linux/slab.h:950 [inline] kzalloc_noprof include/linux/slab.h:1188 [inline] tomoyo_print_bprm security/tomoyo/audit.c:26 [inline] tomoyo_init_log+0x112e/0x1fb0 security/tomoyo/audit.c:264 tomoyo_supervisor+0x353/0x1570 security/tomoyo/common.c:2232 tomoyo_audit_env_log security/tomoyo/environ.c:37 [inline] tomoyo_env_perm+0x151/0x1f0 security/tomoyo/environ.c:64 tomoyo_environ security/tomoyo/domain.c:673 [inline] tomoyo_find_next_domain+0x15cb/0x1aa0 security/tomoyo/domain.c:889 tomoyo_bprm_check_security+0x11b/0x180 security/tomoyo/tomoyo.c:102 security_bprm_check+0x85/0x240 security/security.c:794 search_binary_handler fs/exec.c:1654 [inline] exec_binprm fs/exec.c:1696 [inline] bprm_execve+0x8a2/0x1470 fs/exec.c:1748 do_execveat_common+0x50d/0x690 fs/exec.c:1846 __do_sys_execve fs/exec.c:1930 [inline] __se_sys_execve fs/exec.c:1924 [inline] __x64_sys_execve+0x97/0xc0 fs/exec.c:1924 page last free pid 5497 tgid 5497 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1401 [inline] __free_frozen_pages+0xbf0/0xd00 mm/page_alloc.c:2942 __slab_free+0x274/0x2c0 mm/slub.c:5605 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4569 [inline] slab_alloc_node mm/slub.c:4898 [inline] __kmalloc_cache_noprof+0x2ba/0x660 mm/slub.c:5407 kmalloc_noprof include/linux/slab.h:950 [inline] tomoyo_print_header security/tomoyo/audit.c:156 [inline] tomoyo_init_log+0x195/0x1fb0 security/tomoyo/audit.c:255 tomoyo_supervisor+0x353/0x1570 security/tomoyo/common.c:2232 tomoyo_audit_path_log security/tomoyo/file.c:169 [inline] tomoyo_path_permission+0x25a/0x380 security/tomoyo/file.c:592 tomoyo_check_open_permission+0x2b2/0x470 security/tomoyo/file.c:782 security_file_open+0xa9/0x240 security/security.c:2661 do_dentry_open+0x384/0x14e0 fs/open.c:926 vfs_open+0x3b/0x340 fs/open.c:1081 do_open fs/namei.c:4693 [inline] path_openat+0x2e08/0x3860 fs/namei.c:4852 do_file_open+0x23e/0x4a0 fs/namei.c:4881 do_sys_openat2+0x113/0x200 fs/open.c:1366 Memory state around the buggy address: ffff88801b168700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801b168780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88801b168800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801b168880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801b168900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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