From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 87E3121FF21; Tue, 12 May 2026 17:45:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778607949; cv=none; b=lEMZhFpULDvD3Sy5w+064vbRNEuYNOwHs/tjiIjoR1HLQCi7l0KHwFyE9TXuMKu2MAu1x0mA3/Jx1yHhT0jVi9JVXRb8XIYrXHM/TVQHSgYoOrFOIq1A51LI16VGYyVPjNZ7Oqs9R2f8hrsRMO2q4IE0N2vouob5ld5wxIu3eT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778607949; c=relaxed/simple; bh=jt9WE8hqJcQ2JaUCYjrWAd+vYyjevRuZW98ubAEuCfg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KHRLSDcLNMC/BuJzqbIuXtL/1Uu/VAA7iCuZa+mq3BwzzqvnlZVPS2fGtimI0INhUFK52hloM6yxy9LoB1vZgwG6zlblq8tXPM412BSCy1P4C4ZWATvWAdEUN4wnJ0HtYUAMZcvf9TKzKyeCsvn6rMS6HIdrRF05v//c+pX7Wa4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=16Jh5Md8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="16Jh5Md8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1DBD3C2BCC7; Tue, 12 May 2026 17:45:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778607949; bh=jt9WE8hqJcQ2JaUCYjrWAd+vYyjevRuZW98ubAEuCfg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=16Jh5Md8Jd3+tTULV8AhbBQrFPMSj6BmGY+UPWhF+0SnJxoch/ZUYB7ZLmC7+JNM3 9EUnluTK5nDGNOVHAgTZqMlXtwh+3ryPAN3gePB7kp6Q7QYzhq6cmp/VzFPA4aio+j 5TTdQstKdi6C8jaYWuflBG+ZVpCowpfMXFzGm3mA= 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 6.12 061/206] Bluetooth: virtio_bt: clamp rx length before skb_put Date: Tue, 12 May 2026 19:38:33 +0200 Message-ID: <20260512173934.134128842@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260512173932.810559588@linuxfoundation.org> References: <20260512173932.810559588@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-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) { @@ -227,8 +228,15 @@ 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;