From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) (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 5EEA2420888 for ; Thu, 27 Aug 2026 09:31:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787823102; cv=none; b=GPQwJGSs5fQ2ybpyEUfHhDIQaEDDhN3OpLRSD7U6gxe9eM4ng9QRdZuajkncqhMAuzCEzG/erVB4E5N14Dw6XbRkQfg1yFBpq0ZrkxrSizh2/t6W0y9sFjR5vY5pZRpRJUc/jXHeOovu1oPSL2HKaoIxUGW18jne06Z5ofqtAoY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787823102; c=relaxed/simple; bh=P3fpSl01EL+JlZZ7pcW5UeLGCEoiQ5sAzTvO6JoKySg=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; 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2002:a05:6808:3505:b0:493:a860:5809 with SMTP id 5614622812f47-4b3668b1451mr14124640b6e.4.1787823097520; Thu, 27 Aug 2026 02:31:37 -0700 (PDT) Date: Thu, 27 Aug 2026 02:31:37 -0700 In-Reply-To: <6a8c451c.dbb3a75c.7844.0004.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a9003f9.27659fcc.2ceef7.0012.GAE@google.com> Subject: Re: [syzbot] [media?] KASAN: slab-use-after-free Read in vidtv_bridge_on_new_pkts_avail From: syzbot To: dwlsalmeida@gmail.com, gregkh@linuxfoundation.org, jeffinphilip14@gmail.com, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, mchehab@kernel.org, stable@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 818bebeb63dd drm/xe: Don't hand out the flat CCS storage a.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=14fb5625580000 kernel config: https://syzkaller.appspot.com/x/.config?x=ccca94d2c01b9e78 dashboard link: https://syzkaller.appspot.com/bug?extid=c7fc4794e59786f5b4dc compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1033b415580000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c7fc4794e59786f5b4dc@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in vidtv_bridge_check_demod_lock drivers/media/test-drivers/vidtv/vidtv_bridge.c:145 [inline] BUG: KASAN: slab-use-after-free in vidtv_bridge_on_new_pkts_avail+0x126/0x140 drivers/media/test-drivers/vidtv/vidtv_bridge.c:162 Read of size 8 at addr ffff88802e860118 by task kworker/2:3/5832 CPU: 2 UID: 0 PID: 5832 Comm: kworker/2:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events vidtv_mux_tick Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x13d/0x4b0 mm/kasan/report.c:482 kasan_report+0xdf/0x1c0 mm/kasan/report.c:595 vidtv_bridge_check_demod_lock drivers/media/test-drivers/vidtv/vidtv_bridge.c:145 [inline] vidtv_bridge_on_new_pkts_avail+0x126/0x140 drivers/media/test-drivers/vidtv/vidtv_bridge.c:162 vidtv_mux_tick+0xb95/0x1460 drivers/media/test-drivers/vidtv/vidtv_mux.c:426 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Allocated by task 1: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2e7/0x6b0 mm/slub.c:5484 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] vidtv_demod_i2c_probe+0x6e/0x8a0 drivers/media/test-drivers/vidtv/vidtv_demod.c:421 i2c_device_probe+0x658/0xd10 drivers/i2c/i2c-core-base.c:593 call_driver_probe drivers/base/dd.c:628 [inline] really_probe+0x241/0xa60 drivers/base/dd.c:706 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898 __device_attach_driver+0x1df/0x320 drivers/base/dd.c:1026 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:500 __device_attach+0x1e4/0x4d0 drivers/base/dd.c:1098 device_initial_probe+0xaf/0xd0 drivers/base/dd.c:1153 bus_probe_device+0x64/0x160 drivers/base/bus.c:620 device_add+0x121d/0x1970 drivers/base/core.c:3776 i2c_new_client_device+0x660/0xd30 drivers/i2c/i2c-core-base.c:1020 dvb_module_probe+0x165/0x310 drivers/media/dvb-core/dvbdev.c:1039 vidtv_bridge_probe_demod drivers/media/test-drivers/vidtv/vidtv_bridge.c:354 [inline] vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:430 [inline] vidtv_bridge_probe+0x370/0xa30 drivers/media/test-drivers/vidtv/vidtv_bridge.c:510 platform_probe+0x106/0x1d0 drivers/base/platform.c:1507 call_driver_probe drivers/base/dd.c:628 [inline] really_probe+0x241/0xa60 drivers/base/dd.c:706 __driver_probe_device+0x210/0x460 drivers/base/dd.c:868 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763 driver_register+0x1e2/0x360 drivers/base/driver.c:174 vidtv_bridge_init+0x52/0x80 drivers/media/test-drivers/vidtv/vidtv_bridge.c:602 do_one_initcall+0x11c/0x6f0 init/main.c:1353 do_initcall_level init/main.c:1415 [inline] do_initcalls init/main.c:1431 [inline] do_basic_setup init/main.c:1451 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1666 kernel_init+0x21/0x1e0 init/main.c:1556 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Freed by task 6035: kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2678 [inline] slab_free mm/slub.c:6372 [inline] kfree+0x22b/0x6c0 mm/slub.c:6687 i2c_device_remove+0x81/0x280 drivers/i2c/i2c-core-base.c:632 device_remove+0xcb/0x180 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664 device_del+0x376/0x9b0 drivers/base/core.c:3965 device_unregister+0x1d/0xe0 drivers/base/core.c:4006 i2c_unregister_device+0xf5/0x270 drivers/i2c/i2c-core-base.c:1076 dvb_module_release drivers/media/dvb-core/dvbdev.c:1061 [inline] dvb_module_release+0x69/0x90 drivers/media/dvb-core/dvbdev.c:1055 vidtv_bridge_remove+0xd8/0x140 drivers/media/test-drivers/vidtv/vidtv_bridge.c:556 platform_remove+0x5f/0x80 drivers/base/platform.c:1524 device_remove+0xcb/0x180 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372 unbind_store+0xf8/0x110 drivers/base/bus.c:244 drv_attr_store+0x74/0xb0 drivers/base/bus.c:125 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:145 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:345 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6af/0x1050 fs/read_write.c:687 ksys_write+0x12a/0x250 fs/read_write.c:739 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88802e860000 which belongs to the cache kmalloc-2k of size 2048 The buggy address is located 280 bytes inside of freed 2048-byte region [ffff88802e860000, ffff88802e860800) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88802e864000 pfn:0x2e860 head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000240 ffff88801c042f00 ffffea000071b010 ffffea0000993a10 raw: ffff88802e864000 0000000800080007 00000000f5000000 0000000000000000 head: 00fff00000000240 ffff88801c042f00 ffffea000071b010 ffffea0000993a10 head: ffff88802e864000 0000000800080007 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 15032077504 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871 prep_new_page mm/page_alloc.c:1879 [inline] get_page_from_freelist+0x110d/0x35b0 mm/page_alloc.c:3943 __alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436 alloc_slab_page mm/slub.c:3267 [inline] allocate_slab mm/slub.c:3382 [inline] new_slab+0xa5/0x640 mm/slub.c:3428 refill_objects+0xe3/0x410 mm/slub.c:7305 refill_sheaf mm/slub.c:2805 [inline] __pcs_replace_empty_main+0x372/0x680 mm/slub.c:4677 alloc_from_pcs mm/slub.c:4775 [inline] slab_alloc_node mm/slub.c:4907 [inline] __kmalloc_cache_noprof+0x47b/0x6b0 mm/slub.c:5480 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] wakeup_source_device_create+0x46/0x2e0 drivers/base/power/wakeup_stats.c:144 wakeup_source_sysfs_add+0x1c/0x90 drivers/base/power/wakeup_stats.c:183 wakeup_source_register+0x154/0x3e0 drivers/base/power/wakeup.c:218 device_wakeup_enable+0xce/0x2e0 drivers/base/power/wakeup.c:336 device_init_wakeup include/linux/pm_wakeup.h:238 [inline] alarmtimer_rtc_add_device+0x1da/0x320 kernel/time/alarmtimer.c:99 device_add+0x13cc/0x1970 drivers/base/core.c:3799 cdev_device_add+0x12b/0x270 fs/char_dev.c:553 __devm_rtc_register_device+0x456/0x8d0 drivers/rtc/class.c:418 cmos_do_probe drivers/rtc/rtc-cmos.c:1112 [inline] cmos_platform_probe+0xe3b/0x1100 drivers/rtc/rtc-cmos.c:1451 page last free pid 24 tgid 24 ts 14981723256 stack trace: reset_page_owner include/linux/page_owner.h:26 [inline] __free_pages_prepare mm/page_alloc.c:1418 [inline] free_pages_prepare+0x586/0xe00 mm/page_alloc.c:1463 __free_contig_range_common+0x14f/0x250 mm/page_alloc.c:7060 __free_contig_range mm/page_alloc.c:7105 [inline] free_pages_bulk+0x12a/0x200 mm/page_alloc.c:5322 vm_area_free_pages+0xad/0x2b0 mm/vmalloc.c:3462 vfree mm/vmalloc.c:3511 [inline] vfree+0x108/0x730 mm/vmalloc.c:3485 delayed_vfree_work+0x56/0x80 mm/vmalloc.c:3415 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3387 process_scheduled_works kernel/workqueue.c:3470 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3551 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Memory state around the buggy address: ffff88802e860000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802e860080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88802e860100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88802e860180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88802e860200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== --- 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.