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 0450F2628D; Sat, 30 May 2026 17:53:05 +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=1780163586; cv=none; b=mYTkHMRUNxakSrWFu5HYketXsCkiK3iu95yAJgWDj9U83MpQdUwfDoGCXotERo0Zn1CsQAzQCBtOdj2pq9uSh2X8BVm5JynsB5gkLrYvTSDl47L8Z4JBG670EvFGun7HP/n1aBG3XrTp1i5Hltdqfu3XRk2Ufls1su0FzKbuu7U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780163586; c=relaxed/simple; bh=7Lt0aW9pmQmeuYQMDQRJtdEOrunn5hh/jAfEVlbPyq4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=nSDNurC+uFFjrnFXfcYn8LCJtKEGnenxIDsNE0RvaVghV2HOXPUBdbRfa1+D/da459SmBr/5BpDCMQrHevH6XubWbz3X7959nnc4Y1eouSvAK1cx43ettNGuUaM5BauA+EpJ9QRWDamoT/jwnEWPIO6bfzqUYqcelUISKqbahko= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YSX46KDk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="YSX46KDk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 46FC01F00893; Sat, 30 May 2026 17:53:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1780163584; bh=ptYhgls3vwS5smVjVSYm9Av/YWRK/s3tmHzVank90a4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=YSX46KDkEHtahT4TG0WkjUvLbpBOEnyQykRzEYDoT4kczxKhAFlJJsVJl2Bdp1saA ZIWWZy6S+L1NTRIZe3bkJgU5No23qBFx1KWEKIIQmiS7njAG/Nlb0spvYYjFByBqR0 +dXM80+CDPMOlQW410BHQAAfWmaJnZficfTuZG14= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Soenke Huster , Michael Bommarito , Luiz Augusto von Dentz Subject: [PATCH 5.15 303/776] Bluetooth: virtio_bt: clamp rx length before skb_put Date: Sat, 30 May 2026 18:00:17 +0200 Message-ID: <20260530160248.398888845@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260530160240.228940103@linuxfoundation.org> References: <20260530160240.228940103@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Bommarito commit 21bd244b6de5d2fe1063c23acc93fbdd2b20d112 upstream. virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one(). Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device. The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory. Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle(). Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log. Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length. Fixes: 160fbcf3bfb9 ("Bluetooth: virtio_bt: Use skb_put to set length") Cc: stable@vger.kernel.org Cc: Soenke Huster Signed-off-by: Michael Bommarito Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman --- drivers/bluetooth/virtio_bt.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) --- a/drivers/bluetooth/virtio_bt.c +++ b/drivers/bluetooth/virtio_bt.c @@ -12,6 +12,7 @@ #include #define VERSION "0.1" +#define VIRTBT_RX_BUF_SIZE 1000 enum { VIRTBT_VQ_TX, @@ -33,11 +34,11 @@ static int virtbt_add_inbuf(struct virti struct sk_buff *skb; int err; - skb = alloc_skb(1000, GFP_KERNEL); + skb = alloc_skb(VIRTBT_RX_BUF_SIZE, GFP_KERNEL); if (!skb) return -ENOMEM; - sg_init_one(sg, skb->data, 1000); + sg_init_one(sg, skb->data, VIRTBT_RX_BUF_SIZE); err = virtqueue_add_inbuf(vq, sg, 1, skb, GFP_KERNEL); if (err < 0) { @@ -219,8 +220,15 @@ static void virtbt_rx_work(struct work_s if (!skb) return; - skb_put(skb, len); - virtbt_rx_handle(vbt, skb); + if (!len || len > VIRTBT_RX_BUF_SIZE) { + bt_dev_err_ratelimited(vbt->hdev, + "rx reply len %u outside [1, %u]\n", + len, VIRTBT_RX_BUF_SIZE); + kfree_skb(skb); + } else { + skb_put(skb, len); + virtbt_rx_handle(vbt, skb); + } if (virtbt_add_inbuf(vbt) < 0) return;