From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15DDA389107; Mon, 29 Jun 2026 06:27:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782714475; cv=none; b=KN6eS0hUuiTJLd9cvNyHJYY/L4js3Cx76DYzCZTNbQDmwIn44BumrqbRXxGcju3J0/KXhQ1PCk/CsTEzfCytWNzOOkxV4CALlSiKShhFHwf2YMy/fUjKhMq3TpSjDsIylCorYWLGUnJzt32tCSu10GlkSNSRkvASPJSft7EgFvY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782714475; c=relaxed/simple; bh=CEoNdJbM+G0EYznPjnQPpoh429ZsOMIvdd62gxFGavs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eMVOXBIFbFl0+XbG4Ubb1MafbF+8KiFN5j/MqP/punyjIKqtulCpcuf+AH1HMkBHce3nn6RvxbYhlrtHjh2V/uazwlwdwl1HZRtbNX1HTpEtwaWn/YNnDD1pkp0PPJOilz2R4l2MXBB1yscKBO05cZ6BbzbNPGnSA2E2TqjczMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XUoHVk1I; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XUoHVk1I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10E361F000E9; Mon, 29 Jun 2026 06:27:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782714473; bh=8diiuVvstmh7e4zfvwC2TUp3d+EiAMlelXELW0j1hjI=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=XUoHVk1IkDHpBf/rl1gBmvmCwGQXinaUwLcSEq8EvP3XGURvE/T00WCGDMaDt9/Ha ClQlj6YrvXnwFi6pa2mQYOM69K0jgcIK24NBAjAk1+JOm9DWkAutR2dsUeNNtxdbOS gq6WMK/Zz9vb8+mVM4lzCx0LF/BC84Lgwd/AsqDWo8s/l9nG/cgz1D+Fus+SQXB8qq dQ3FWrXaWWDEyfbHi5nHuqSMBPSjfaebnbmkQU+g27mXs33Jn4cPRbf/4AiRWt25Ro LeieO9Rj3+pCr4LnifXrjcDB2MgHMmur19W0Ki1FDuerhlZKi1gNC92u45zL7+GBLo 4azJoKnYhHOwQ== Message-ID: <85cf5045-b52b-4aaa-a038-ca1b856b55f9@kernel.org> Date: Mon, 29 Jun 2026 08:27:48 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: WARNING in usb_free_urb To: sanan.hasanou@gmail.com, vbabka@suse.cz, akpm@linux-foundation.org, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, harry.yoo@oracle.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: syzkaller@googlegroups.com, contact@pgazz.com, Greg Kroah-Hartman , linux-usb@vger.kernel.org, Mauro Carvalho Chehab , linux-media@vger.kernel.org References: <6a3eeead.7fb353d3.354599.b0b0@mx.google.com> From: "Vlastimil Babka (SUSE)" Content-Language: en-US Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/26/26 23:27, sanan.hasanou@gmail.com wrote: > Good day, dear maintainers, > > We found a bug using a modified version of syzkaller. Subject says "usb_free_urb" but you only CC'd slab maintainers, where slab slab is most likely a victim here of e.g. double kfree() or a kfree() of otherwise broken pointer. Ccing USB and EM28XX maintainers. But they can feel free to ignore this per the next point. > Kernel Branch: 7.0-rc1 Why use such a version for fuzzing? rc1 will have many bugs that are already fixed in 7.0 final. And it's not even latest, 7.1 was released 2 weeks ago too. > Kernel Config: > Unfortunately, we don't have any reproducer for this bug yet. > Thank you! > > Best regards, > Sanan Hasanov > > 179683 pages reserved > 0 pages cma reserved > Memory cgroup min protection 0kB -- low protection 0kB > ------------[ cut here ]------------ > !PageLargeKmalloc(page) > WARNING: mm/slub.c:6352 at free_large_kmalloc+0xb3/0x160 mm/slub.c:6352, CPU#1: kworker/1:4/12317 A kfree() was attempted on a pointer that's neither from a slab page nor a large kmalloc page. Might be double free or corrupted. > Modules linked in: > CPU: 1 UID: 0 PID: 12317 Comm: kworker/1:4 Tainted: G L 7.0.0-rc1 #1 PREEMPT(full) > Tainted: [L]=SOFTLOCKUP > Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > Workqueue: events request_module_async > RIP: 0010:free_large_kmalloc+0xb3/0x160 mm/slub.c:6352 > Code: 25 00 00 00 ff 3d 00 00 00 f8 0f 85 a6 00 00 00 c7 43 30 ff ff ff ff 48 89 df 44 89 f6 e8 45 d9 fc ff 5b 41 5e 41 5f 5d c3 90 <0f> 0b 90 48 89 df 48 c7 c6 b7 4c 72 8d e8 cb e8 08 ff eb e4 90 0f > RSP: 0018:ffffc900028e76f8 EFLAGS: 00010287 > RAX: 00000000f0000000 RBX: ffffea00019a5c00 RCX: ffff888067550001 > RDX: 0000000000000000 RSI: ffff888066970000 RDI: ffffea00019a5c00 > RBP: ffffc900028e7710 R08: ffff888049c40603 R09: 1ffff110093880c0 > R10: dffffc0000000000 R11: ffffed10093880c1 R12: ffff888066970000 > R13: ffffffff870bc0f1 R14: 0000000000000000 R15: dffffc0000000000 > FS: 0000000000000000(0000) GS:ffff8880ef136000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fba7e4bf008 CR3: 000000005776b000 CR4: 00000000000006f0 > Call Trace: > > kfree+0xae/0x630 mm/slub.c:6437 > urb_destroy drivers/usb/core/urb.c:25 [inline] static void urb_destroy(struct kref *kref) { struct urb *urb = to_urb(kref); if (urb->transfer_flags & URB_FREE_BUFFER) kfree(urb->transfer_buffer); <--- this one kfree(urb); } > kref_put include/linux/kref.h:65 [inline] > usb_free_urb+0xd1/0x120 drivers/usb/core/urb.c:96 USB layer itself is likely also not the root cause. > em28xx_uninit_usb_xfer+0x165/0x310 drivers/media/usb/em28xx/em28xx-core.c:833 > em28xx_alloc_urbs+0xf2a/0x1130 drivers/media/usb/em28xx/em28xx-core.c:-1 > em28xx_dvb_init+0x2b0/0x4a20 drivers/media/usb/em28xx/em28xx-dvb.c:-1 > em28xx_init_extension+0x121/0x1d0 drivers/media/usb/em28xx/em28xx-core.c:1117 So it might be this driver doing something wrong? > request_module_async+0x5e/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3457 > process_one_work kernel/workqueue.c:3275 [inline] > process_scheduled_works+0xae1/0x1800 kernel/workqueue.c:3358 > worker_thread+0xa0f/0xf70 kernel/workqueue.c:3439 > kthread+0x37d/0x470 kernel/kthread.c:467 > ret_from_fork+0x507/0xb90 arch/x86/kernel/process.c:158 > ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:245 > > > <<<<<<<<<<<<<<< tail report >>>>>>>>>>>>>>> > > Modules linked in: > CPU: 1 UID: 0 PID: 12317 Comm: kworker/1:4 Tainted: G L 7.0.0-rc1 #1 PREEMPT(full) > Tainted: [L]=SOFTLOCKUP > Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > Workqueue: events request_module_async > RIP: 0010:free_large_kmalloc+0xb3/0x160 > Code: 25 00 00 00 ff 3d 00 00 00 f8 0f 85 a6 00 00 00 c7 43 30 ff ff ff ff 48 89 df 44 89 f6 e8 45 d9 fc ff 5b 41 5e 41 5f 5d c3 90 <0f> 0b 90 48 89 df 48 c7 c6 b7 4c 72 8d e8 cb e8 08 ff eb e4 90 0f > RSP: 0018:ffffc900028e76f8 EFLAGS: 00010287 > RAX: 00000000f0000000 RBX: ffffea00019a5c00 RCX: ffff888067550001 > RDX: 0000000000000000 RSI: ffff888066970000 RDI: ffffea00019a5c00 > RBP: ffffc900028e7710 R08: ffff888049c40603 R09: 1ffff110093880c0 > R10: dffffc0000000000 R11: ffffed10093880c1 R12: ffff888066970000 > R13: ffffffff870bc0f1 R14: 0000000000000000 R15: dffffc0000000000 > FS: 0000000000000000(0000) GS:ffff8880ef136000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fba7e4bf008 CR3: 000000005776b000 CR4: 00000000000006f0 > Call Trace: > > kfree+0xae/0x630 > usb_free_urb+0xd1/0x120 > em28xx_uninit_usb_xfer+0x165/0x310 > em28xx_alloc_urbs+0xf2a/0x1130 > em28xx_dvb_init+0x2b0/0x4a20 > em28xx_init_extension+0x121/0x1d0 > request_module_async+0x5e/0x80 > process_scheduled_works+0xae1/0x1800 > worker_thread+0xa0f/0xf70 > kthread+0x37d/0x470 > ret_from_fork+0x507/0xb90 > ret_from_fork_asm+0x11/0x20 > > Kernel panic - not syncing: kernel: panic_on_warn set ... > CPU: 1 UID: 0 PID: 12317 Comm: kworker/1:4 Tainted: G L 7.0.0-rc1 #1 PREEMPT(full) > Tainted: [L]=SOFTLOCKUP > Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > Workqueue: events request_module_async > Call Trace: > > __dump_stack+0x21/0x30 > dump_stack_lvl+0x2b/0x150 > dump_stack+0x19/0x20 > vpanic+0x53e/0xa20 > panic+0xb9/0xc0 > __warn+0x320/0x500 > __report_bug+0x28d/0x500 > report_bug+0x175/0x220 > handle_bug+0x9c/0x200 > exc_invalid_op+0x1f/0x50 > asm_exc_invalid_op+0x1f/0x30 > RIP: 0010:free_large_kmalloc+0xb3/0x160 > Code: 25 00 00 00 ff 3d 00 00 00 f8 0f 85 a6 00 00 00 c7 43 30 ff ff ff ff 48 89 df 44 89 f6 e8 45 d9 fc ff 5b 41 5e 41 5f 5d c3 90 <0f> 0b 90 48 89 df 48 c7 c6 b7 4c 72 8d e8 cb e8 08 ff eb e4 90 0f > RSP: 0018:ffffc900028e76f8 EFLAGS: 00010287 > RAX: 00000000f0000000 RBX: ffffea00019a5c00 RCX: ffff888067550001 > RDX: 0000000000000000 RSI: ffff888066970000 RDI: ffffea00019a5c00 > RBP: ffffc900028e7710 R08: ffff888049c40603 R09: 1ffff110093880c0 > R10: dffffc0000000000 R11: ffffed10093880c1 R12: ffff888066970000 > R13: ffffffff870bc0f1 R14: 0000000000000000 R15: dffffc0000000000 > kfree+0xae/0x630 > usb_free_urb+0xd1/0x120 > em28xx_uninit_usb_xfer+0x165/0x310 > em28xx_alloc_urbs+0xf2a/0x1130 > em28xx_dvb_init+0x2b0/0x4a20 > em28xx_init_extension+0x121/0x1d0 > request_module_async+0x5e/0x80 > process_scheduled_works+0xae1/0x1800 > worker_thread+0xa0f/0xf70 > kthread+0x37d/0x470 > ret_from_fork+0x507/0xb90 > ret_from_fork_asm+0x11/0x20 > > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > <<<<<<<<<<<<<<< tail report >>>>>>>>>>>>>>>