From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) (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 D15B0363C73 for ; Fri, 20 Mar 2026 11:05:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774004704; cv=none; b=um3MLnrXdXrSx0YsMwLDN/fe45UJ2pkyvqebxwPr9l9h3KR94fHHtSya6MWTL69vNTPD3s6ve4B0wwuX9wzrD9EHyZveGzz9PCvJ/B98ERKnG0nuTLs5qFC6QvaX+ffc2CEJ9qeXjIHK2jLpRPkeLIIyAbahd1OYoEGYUy6O7Xg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774004704; c=relaxed/simple; bh=CqrZoWb4qkDcy6RTjqruJPmNBx8PMMNE1u9+IekEtJg=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=KYw3jBMUqOMQYhn+pJrWN8+Br+KrMADt3Hqq+nQ9FU/jJ5JD8+QBMBh+RC2LFIBdwfDXD3fl+vDMWp7orVXeoCPuUbT0JD+SggZf+bME3UiVrAaQNTSI8vcsHwfe3Cn3V62efdR4UC+UULDC6o6mrMARVADq48JoBAjCGyR7vmE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.161.70 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo1-f70.google.com with SMTP id 006d021491bc7-67c0d7d179eso24873068eaf.1 for ; Fri, 20 Mar 2026 04:05:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774004702; x=1774609502; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=ZR77SX4Zn1eDKqB6grm4bj54vDdaPAvs0wpKu04wQZ0=; b=dqUcqTjaL36X59l8eWxxjmobzfxR5bolKr3nce+O+4TmkkklTrzWS4FmiTlQGblq0L 34KFJjsew3exfuaz15QbNKwWe9vzRPEDhvRSJup9SoCPNIp6bJUzxww8DpiZ1a+DIOgX mqo5Nk3/+i5CWFwJmZC5/Qx7qJxTPzE7XmMS5bmVeFST7Hax5GCqMAxwXRo9yHcsJlZ7 bVLCjbmcp007akRkGEYHBaMGxlkrwQdb6i50OHGhAcK+5zGDV+WXMBx8pW/9AVoMIlca MyAEhPfnvQGJ78iM/bOLMqhqZDt7yiNxMp5YR7iwUwnUEP5sPojzdhbqK/cNRu9DoMG8 tO7A== X-Forwarded-Encrypted: i=1; AJvYcCUOFw3E/POmE7SQM/1L7v46BOV3iuQvQoB5ih/KKEAbjvdNI2v2TZkYp/Hl6WFE3FfF/dHZuO7bRIoq+/A=@vger.kernel.org X-Gm-Message-State: AOJu0YxCLuIwBCftmHRREToVLGqfoWdzWWsU3ShNMW7yV+Cer+3URs5p WZw8V9TUVMPfKwvDz4+/qxWO8OJhgNuS+MbWfif2H1JdE7uEHdrHcekHd5G232UWd99cqdBg+BH i2sM7JTqtw1/w3RtRZv/iTMGjRADA0EbxwWmuoVTHWo4fwFGgSEy0TxnRsHw= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:6707:b0:67c:2d5e:e9dd with SMTP id 006d021491bc7-67c2d5eedd1mr16006eaf.41.1774004701800; Fri, 20 Mar 2026 04:05:01 -0700 (PDT) Date: Fri, 20 Mar 2026 04:05:01 -0700 In-Reply-To: <20260320062304.1097949-1-kartikey406@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69bd29dd.050a0220.3bf4de.001e.GAE@google.com> Subject: Re: [syzbot] [media?] [usb?] KASAN: slab-use-after-free Read in v4l2_open From: syzbot To: kartikey406@gmail.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: KASAN: slab-use-after-free Read in v4l2_open ================================================================== 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 ffff88801b71c858 by task v4l_id/6825 CPU: 1 UID: 0 PID: 6825 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: 0033:0x7f85abca7407 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:00007ffeda7065e0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f85ac45c880 RCX: 00007f85abca7407 RDX: 0000000000000000 RSI: 00007ffeda706f1c RDI: ffffffffffffff9c RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 R13: 00007ffeda706830 R14: 00007f85ac5c3000 R15: 000056264efca4d8 Allocated by task 6729: 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+0x10c/0x2ff0 drivers/media/usb/em28xx/em28xx-video.c:2538 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117 process_one_work+0x9a3/0x1710 kernel/workqueue.c:3288 process_scheduled_works kernel/workqueue.c:3379 [inline] worker_thread+0xba8/0x11e0 kernel/workqueue.c:3465 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 6729: 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+0x1c5/0x640 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+0x16c8/0x2ff0 drivers/media/usb/em28xx/em28xx-video.c:2907 em28xx_init_extension+0x120/0x1c0 drivers/media/usb/em28xx/em28xx-core.c:1117 process_one_work+0x9a3/0x1710 kernel/workqueue.c:3288 process_scheduled_works kernel/workqueue.c:3379 [inline] worker_thread+0xba8/0x11e0 kernel/workqueue.c:3465 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 ffff88801b71c000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 2136 bytes inside of freed 8192-byte region [ffff88801b71c000, ffff88801b71e000) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1b718 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 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5958, tgid 5958 (syz-executor), ts 82175242574, free_ts 82087244705 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] __do_kmalloc_node mm/slub.c:5291 [inline] __kvmalloc_node_noprof+0x657/0x8a0 mm/slub.c:6824 kvmalloc_array_node_noprof include/linux/slab.h:1216 [inline] __ptr_ring_init_queue_alloc_noprof include/linux/ptr_ring.h:481 [inline] ptr_ring_resize_noprof include/linux/ptr_ring.h:601 [inline] tun_attach+0x891/0x1590 drivers/net/tun.c:727 tun_net_init+0x309/0x3d0 drivers/net/tun.c:940 register_netdevice+0x6d1/0x1cf0 net/core/dev.c:11367 tun_set_iff+0x844/0xf00 drivers/net/tun.c:2807 __tun_chr_ioctl+0x7c8/0x1e30 drivers/net/tun.c:3088 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 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 5958 tgid 5958 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] kzalloc_noprof include/linux/slab.h:1188 [inline] inet_alloc_ifa net/ipv4/devinet.c:212 [inline] inet_rtm_to_ifa net/ipv4/devinet.c:904 [inline] inet_rtm_newaddr+0x5d8/0x1ad0 net/ipv4/devinet.c:980 rtnetlink_rcv_msg+0x7d5/0xbe0 net/core/rtnetlink.c:6958 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec+0x112/0x150 net/socket.c:796 __sock_sendmsg net/socket.c:811 [inline] __sys_sendto+0x3ff/0x590 net/socket.c:2279 __do_sys_sendto net/socket.c:2286 [inline] __se_sys_sendto net/socket.c:2282 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2282 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: ffff88801b71c700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801b71c780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88801b71c800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801b71c880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801b71c900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== Tested on: commit: b5d083a3 Add linux-next specific files for 20260319 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=11a8f2da580000 kernel config: https://syzkaller.appspot.com/x/.config?x=9e197b084b913f8d 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 patch: https://syzkaller.appspot.com/x/patch.diff?x=1013cada580000