From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794591223; b=v8o6vzqp6U4Gi6VcFAfSMO7FDw6805mHZeOBOfq1hal8DJNoltNqAFBjoYFeUa5sFEDu Wj82+SBJbbRQhKGtK24v64i5At/n36nCQRyr8waxbu1FSDspdwSkdaIj16HUrH+rQ2wl1 ItR/6XhDV6agFMgnB9EKgQqkg0QQkyUGirnOP2x4zPtI9SrhZVq0J+Q1J1oD8niMfErDg FhTXgUOksdW5ZdsV8FnQev6sN/vNcDv0IvD/8A95e5NkQ1N1Owww0oTUtsmW5Eii3Cb0z nIdT0zqfHPlmmYQro29+LCPQZTwbVDg6S6DafPyYNEGCusDVFLh2tLYuVw1lp2Nv2aQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794591223; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=1vZdX4PZoQlbXHd0U2btOYYXgCOIS1+naQoixjEsINY=; b=MMMIJwLPyFCTRc+5MInWdSM259a83nbjTdKBg3N7NALN8iXUIiKaL716pMIM4xyJFxrN Vaze2t+01OaCi78LVYeGQv0l7JsnRk5YELY7oXjXkSQA3KYmyIzhl6b3/eio0aE450fHZ 3EE7QQwjk7dN0DeHt/adBzxou4LNAAGcTKOWrIS0gC78zp6dvLjBtxjV625tR07KFiJjt J16gptRSt4nxs6kd8SdVSe5ct1JCu9FK6QydJjZ7FZmGgagH64co4VujyXLP9UGr0WJef m0ow1TLctFo0NWjg9h0FQZKa5nKj4l+m4KoQgM3ik8XRh00gVv7/LIhkIsagSeaZzEg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=x9k7D0El; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 681B06075E2D; Fri, 13 Nov 2026 17:33:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=x9k7D0El Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14F201F000C4; Fri, 13 Nov 2026 17:33:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794591223; bh=1vZdX4PZoQlbXHd0U2btOYYXgCOIS1+naQoixjEsINY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=x9k7D0ElZwOE6zz5y3d8Ppllz7UBkSf1Ppt+3+oUCrbYL6ESGLWdBfooCRb0956xE LvRL/lPXnmBIWd4F6qPT2p3GGn0eBctEYb500IswSEoIwyZ3uCeqITJkCiQuxZDP6e zNBg4zR2cW6vzYcYGVfGTs6LhChXjgBgsvT3ggTI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Daehyeon Ko <4ncienth@gmail.com>, Stefano Garzarella , "Michael S. Tsirkin" , Paolo Abeni , Sasha Levin Subject: [PATCH 6.12 337/670] vhost/vsock: size receive SKBs from declared payload Date: Fri, 13 Nov 2026 10:48:21 -0500 Message-ID: <20261113153823.279598325@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153811.177190860@linuxfoundation.org> References: <20261113153811.177190860@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daehyeon Ko <4ncienth@gmail.com> [ Upstream commit d5e912448cd98b261eba8e35ab838f2dc69a79f5 ] vhost_vsock_alloc_skb() sizes the skb from iov_length(), the total guest descriptor length. virtio_transport_inc_rx_pkt() instead adds hdr->len to rx_bytes and buf_used, and budgets each queued skb as SKB_TRUESIZE(0). The guest controls the descriptor length and hdr->len independently. A guest can therefore provide a 64 KiB descriptor while declaring a zero payload. The descriptor-sized skb remains queued, rx_bytes and buf_used remain unchanged, and only the fixed queue-entry budget limits retention. This is not a lifetime leak: the skb is freed when dequeued or at socket teardown. Repeating this across connections can nevertheless exhaust host memory. On Linux v7.2, 455 such descriptors retained 30,255,680 bytes for a 262,144-byte receive buffer; a full-payload control retained 265,984 bytes. Vhost previously read hdr->len and allocated pkt->buf from that value. The conversion from virtio_vsock_pkt to sk_buff instead allocated receive skbs from the descriptor length, introducing the allocation-accounting mismatch. Copy the header into a stack object and validate hdr->len before allocating the skb. Size the allocation as sizeof(hdr) + payload_len so descriptor capacity no longer determines queued memory. Check payload_len against len - sizeof(hdr) to avoid addition overflow on 32-bit hosts. Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff") Cc: stable@vger.kernel.org Signed-off-by: Daehyeon Ko <4ncienth@gmail.com> Reviewed-by: Stefano Garzarella Acked-by: Michael S. Tsirkin Link: https://patch.msgid.link/20261004235101.1464007-1-4ncienth@gmail.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin --- drivers/vhost/vsock.c | 34 ++++++++++++++++------------------ 1 file changed, 16 insertions(+), 18 deletions(-) diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index 65297f245b272..f00182e9efec0 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -331,7 +331,7 @@ static struct sk_buff * vhost_vsock_alloc_skb(struct vhost_virtqueue *vq, unsigned int out, unsigned int in) { - struct virtio_vsock_hdr *hdr; + struct virtio_vsock_hdr hdr; struct iov_iter iov_iter; struct sk_buff *skb; size_t payload_len; @@ -349,34 +349,32 @@ vhost_vsock_alloc_skb(struct vhost_virtqueue *vq, len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM) return NULL; - /* len contains both payload and hdr */ - skb = virtio_vsock_alloc_skb(len, GFP_KERNEL); - if (!skb) - return NULL; - iov_iter_init(&iov_iter, ITER_SOURCE, vq->iov, out, len); - hdr = virtio_vsock_hdr(skb); - nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter); - if (nbytes != sizeof(*hdr)) { + nbytes = copy_from_iter(&hdr, sizeof(hdr), &iov_iter); + if (nbytes != sizeof(hdr)) { vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n", - sizeof(*hdr), nbytes); - kfree_skb(skb); + sizeof(hdr), nbytes); return NULL; } - payload_len = le32_to_cpu(hdr->len); + payload_len = le32_to_cpu(hdr.len); + + /* The pkt is too big or the length in the header is invalid */ + if (payload_len > len - sizeof(hdr)) + return NULL; + + /* Allocate only for the payload declared in the header. */ + skb = virtio_vsock_alloc_skb(payload_len + sizeof(hdr), GFP_KERNEL); + if (!skb) + return NULL; + + memcpy(virtio_vsock_hdr(skb), &hdr, sizeof(hdr)); /* No payload */ if (!payload_len) return skb; - /* The pkt is too big or the length in the header is invalid */ - if (payload_len + sizeof(*hdr) > len) { - kfree_skb(skb); - return NULL; - } - virtio_vsock_skb_put(skb, payload_len); if (skb_copy_datagram_from_iter(skb, 0, &iov_iter, payload_len)) { -- 2.53.0