From nobody Fri Oct 3 20:55:18 2025 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) (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 C9E542C0F7B for ; Mon, 25 Aug 2025 08:41:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.61.82.184 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756111296; cv=none; b=c4LbDps2qDVxnZE4VVbNp4VXvZbRebUieJ0d8fc1cVsGGblgCHzLGSnKn4BB8nqlAzSs1fOvD85Boq3LkqfReYzjCjXbTzYJeynG7yQckeKbYWUdsyyWKGeJLzQBlubbGpD+zwDP3t+BJ7VbuFop65F7pMo11SJ+C/f+FgVhiM0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756111296; c=relaxed/simple; bh=Jfa1THEcp2NSGVGu9eZpmlzsfemWMV56Bx1xwURGSvc=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=L0jruYUNMkDBbH/Mv+ZbDYoE3px/KX7cuYph/6glshRLuUu94DQUP7El01ZlD1C1yHKe/a4Az+29WJrukIV+OZp9jFoJF2Q7avNeCtantTRmyuc5LU+S+61Omt3CZLG99w/KI/lQ1ix3FMEG43W70C7GnTXwPz+ZZi6nkpqL1oU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com; spf=pass smtp.mailfrom=mediatek.com; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b=aZ3knCbI; arc=none smtp.client-ip=210.61.82.184 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=mediatek.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mediatek.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="aZ3knCbI" X-UUID: 4b54a67a818f11f0b33aeb1e7f16c2b6-20250825 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC:To:From; bh=Tj8a6GPuOmdWC97QKAJpys6LnXM9wpEnatX8NPRY2Qw=; b=aZ3knCbI68NQGGZOMKsi5/62yK9Gogkbn9hXqdtYGeWKSuFDuv0J/ULiNlbWlUjy+svS3umeQz5FrTB2BZlGIj1T+Y0khjouZJw7d6AGX9HdZQXuyYXtyVmEx+ijF5nuNDhCMDdpAMcgGtBUzYHNa+eRwmjywXoUkaRQVsL7MOM=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.3,REQID:dafbeef3-e35e-4499-b7cb-05f520da4fa7,IP:0,UR L:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION:r elease,TS:0 X-CID-META: VersionHash:f1326cf,CLOUDID:f4e87e7a-966c-41bd-96b5-7d0b3c22e782,B ulkID:nil,BulkQuantity:0,Recheck:0,SF:81|82|102,TC:-5,Content:0|15|50,EDM: -3,IP:nil,URL:0,File:nil,RT:nil,Bulk:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0, AV:0,LES:1,SPR:NO,DKR:0,DKP:0,BRR:0,BRE:0,ARC:0 X-CID-BVR: 3,DMD|SSN|SDN X-CID-BAS: 3,DMD|SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 4b54a67a818f11f0b33aeb1e7f16c2b6-20250825 Received: from mtkmbs14n1.mediatek.inc [(172.21.101.75)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 263565723; Mon, 25 Aug 2025 16:41:29 +0800 Received: from mtkmbs13n1.mediatek.inc (172.21.101.193) by MTKMBS09N2.mediatek.inc (172.21.101.94) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.39; Mon, 25 Aug 2025 16:41:28 +0800 Received: from mbjsdccf07.gcn.mediatek.inc (10.15.20.246) by mtkmbs13n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1258.39 via Frontend Transport; Mon, 25 Aug 2025 16:41:27 +0800 From: To: Arnd Bergmann , Greg Kroah-Hartman , Matthias Brugger , AngeloGioacchino Del Regno CC: , , Xion Wang , , , Subject: [PATCH 1/1] misc: Prevent double registration and deregistration of miscdevice Date: Mon, 25 Aug 2025 16:45:47 +0800 Message-ID: <20250825084556.10358-2-xion.wang@mediatek.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20250825084556.10358-1-xion.wang@mediatek.com> References: <20250825084556.10358-1-xion.wang@mediatek.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Xion Wang When repeated calls to misc_register() or misc_deregister() on the same miscdevice could lead to kernel crashes or misc_list corruption due to multiple INIT_LIST_HEAD or list_del operations on the same list node. This patch improves the robustness of the misc device driver by preventing both double registration and double deregistration of miscdevice instances. Signed-off-by: Xion Wang --- drivers/char/misc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/char/misc.c b/drivers/char/misc.c index 558302a64dd9..2f8666312966 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -210,6 +210,9 @@ int misc_register(struct miscdevice *misc) int err =3D 0; bool is_dynamic =3D (misc->minor =3D=3D MISC_DYNAMIC_MINOR); =20 + if (WARN_ON(misc->this_device)) + return -EEXIST; + INIT_LIST_HEAD(&misc->list); =20 mutex_lock(&misc_mtx); @@ -251,6 +254,7 @@ int misc_register(struct miscdevice *misc) misc->minor =3D MISC_DYNAMIC_MINOR; } err =3D PTR_ERR(misc->this_device); + misc->this_device =3D NULL; goto out; } =20 @@ -275,12 +279,13 @@ EXPORT_SYMBOL(misc_register); =20 void misc_deregister(struct miscdevice *misc) { - if (WARN_ON(list_empty(&misc->list))) + if (WARN_ON(!misc->this_device)) return; =20 mutex_lock(&misc_mtx); list_del(&misc->list); device_destroy(&misc_class, MKDEV(MISC_MAJOR, misc->minor)); + misc->this_device =3D NULL; misc_minor_free(misc->minor); mutex_unlock(&misc_mtx); } --=20 2.45.2