From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) (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 4BF642405EB; Mon, 17 Aug 2026 09:53:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=60.244.123.138 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786960427; cv=none; b=dxA1PYG34T6gqiCR5B4YZya//hknXXn8mG6mPDQQZgb1TB5Yn+I2cqyRMbb4YCtA/baqgK87GOs3XawLHVQz+OSNdKj5fne5vaqWBIyj9QZsi8HCkOqxcq3idI7Sgm70gLVesJaJO3yI954zDNp7AVa7T89A7pb17d3gDGjmrIY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786960427; c=relaxed/simple; bh=+4RhYZTXbdQnfGNtD46n1CN1hMM6s8Z6NRKjmgSMKrA=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YridBghcszQOxaRxseatfdbUhm3InJdnaliuISoQ6RVo9BDJ5x7sUriCsLKxTagLyzPInNZBLHBBbG4mMETzVSwuYnNNJbdbq4ZZ7FEPEQ63wnylg+0cq5ziUxpcWrFz8asHDu2OIsIXwkHzdv49GAMQo9B/67O414JbhN+6bXY= 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=NDwsQ0Sk; arc=none smtp.client-ip=60.244.123.138 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="NDwsQ0Sk" X-UUID: 83da6d089a2111f1b1788b6acf885367-20260817 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=FZSbhQ3cD5a+jfL9nWiOGzu0+h/kcHpfHBnZa/AsHO8=; b=NDwsQ0SkbMmADU9G0XBd/5xrv1Xb8JrXRnY2q+KswDXxprpNWk5MNR4/DHkSKNtIEXs/4y2NYeCtKaMTMZsrDnmR0sOarNjt1+0Wph/ONXMNGDRE+T4PWQnC7VMkSyTH+r/LpInDDsdVxPYkD3bfkP5uGxlND84yqgHwz0RhkAc=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.3.19,REQID:ba44e436-13f0-44cd-82ca-5ba1ef37e106,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:7db8b62,CLOUDID:faf48ee2-71f1-405e-92eb-6802d6af74fd,B ulkID:nil,BulkQuantity:0,SF:81|82|102|836|865|888|898,TC:-5,Content:0|15|5 0|99,EDM:-3,IP:nil,URL:0,File:130,RT:0,Bulk:nil,QS:nil,BEC:-1,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: 2,SSN|SDN X-CID-BAS: 2,SSN|SDN,0,_ X-CID-FACTOR: TF_CID_SPAM_SNR X-CID-RHF: D41D8CD98F00B204E9800998ECF8427E X-UUID: 83da6d089a2111f1b1788b6acf885367-20260817 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1785870007; Mon, 17 Aug 2026 17:53:36 +0800 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by MTKMBS14N2.mediatek.inc (172.21.101.76) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.29; Mon, 17 Aug 2026 17:53:34 +0800 Received: from mtksitap99.mediatek.inc (10.233.130.16) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.2562.29 via Frontend Transport; Mon, 17 Aug 2026 17:53:34 +0800 From: Chris Lu To: Marcel Holtmann , Johan Hedberg , Luiz Von Dentz CC: Sean Wang , Will Lee , SS Wu , linux-bluetooth , linux-kernel , linux-mediatek , Chris Lu Subject: [PATCH 2/2] Bluetooth: btmtksdio: Fix out-of-bounds DMA read in the TX path Date: Mon, 17 Aug 2026 17:53:32 +0800 Message-ID: <20260817095332.182994-3-chris.lu@mediatek.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20260817095332.182994-1-chris.lu@mediatek.com> References: <20260817095332.182994-1-chris.lu@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: 8bit Content-Type: text/plain btmtksdio_tx_packet() rounds the transfer size up to the SDIO block size of 256 bytes, but hands the host controller the SKB buffer as is: err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data, round_up(skb->len, MTK_SDIO_BLOCK_SIZE)); Only skb->len bytes hold packet data, so the controller reads up to 255 bytes of uninitialised memory and sends it to the device over the SDIO bus. Depending on how much tailroom slack the SKB allocation happens to carry, that read can also extend past the end of the buffer. Compute the padded length up front, ensure the SKB has tailroom for it, and zero-fill the padding with skb_put_zero(). skb->len then covers the padding, so sdio_writesb() no longer needs to round up. byte_tx keeps counting the header and the payload only, and the error path restores the SKB so that the caller can requeue it. Writing behind skb->tail is only safe because the driver owns the buffer, which "Bluetooth: btmtksdio: Take exclusive ownership of the SKB before TX" ensures. Fixes: 9aebfd4a2200 ("Bluetooth: mediatek: add support for MediaTek MT7663S and MT7668S SDIO devices") Signed-off-by: Chris Lu Assisted-by: Claude:claude-opus-5 --- drivers/bluetooth/btmtksdio.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/bluetooth/btmtksdio.c b/drivers/bluetooth/btmtksdio.c index bcbbcf8ecc24..b7f0be7fc42a 100644 --- a/drivers/bluetooth/btmtksdio.c +++ b/drivers/bluetooth/btmtksdio.c @@ -272,6 +272,7 @@ static int btmtksdio_tx_packet(struct btmtksdio_dev *bdev, struct sk_buff *skb) { struct mtkbtsdio_hdr *sdio_hdr; + unsigned int len, pad_len; int err; /* Make sure that the data buffer is not shared with anyone else and @@ -281,6 +282,18 @@ static int btmtksdio_tx_packet(struct btmtksdio_dev *bdev, if (err < 0) return err; + /* The transfer is rounded up to the SDIO block size, so the buffer + * has to provide tailroom for the padding as well + */ + len = skb->len + sizeof(*sdio_hdr); + pad_len = round_up(len, MTK_SDIO_BLOCK_SIZE) - len; + + if (unlikely(skb_tailroom(skb) < pad_len)) { + err = pskb_expand_head(skb, 0, pad_len, GFP_ATOMIC); + if (err < 0) + return err; + } + /* Prepend MediaTek SDIO Specific Header */ skb_push(skb, sizeof(*sdio_hdr)); @@ -289,19 +302,22 @@ static int btmtksdio_tx_packet(struct btmtksdio_dev *bdev, sdio_hdr->reserved = cpu_to_le16(0); sdio_hdr->bt_type = hci_skb_pkt_type(skb); + /* Zero the padding so that no uninitialised memory is sent out */ + skb_put_zero(skb, pad_len); + clear_bit(BTMTKSDIO_HW_TX_READY, &bdev->tx_state); - err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data, - round_up(skb->len, MTK_SDIO_BLOCK_SIZE)); + err = sdio_writesb(bdev->func, MTK_REG_CTDR, skb->data, skb->len); if (err < 0) - goto err_skb_pull; + goto err_skb_restore; - bdev->hdev->stat.byte_tx += skb->len; + bdev->hdev->stat.byte_tx += len; kfree_skb(skb); return 0; -err_skb_pull: +err_skb_restore: + skb_trim(skb, len); skb_pull(skb, sizeof(*sdio_hdr)); return err; -- 2.45.2