This is a note to let you know that I've just added the patch titled 9p/xen: check logical size for buffer size to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: 9p-xen-check-logical-size-for-buffer-size.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 6ae717773f7be57e537074a45b335e856d5df630 Author: Dominique Martinet <asmadeus@xxxxxxxxxxxxx> Date: Fri Nov 18 22:44:41 2022 +0900 9p/xen: check logical size for buffer size [ Upstream commit 391c18cf776eb4569ecda1f7794f360fe0a45a26 ] trans_xen did not check the data fits into the buffer before copying from the xen ring, but we probably should. Add a check that just skips the request and return an error to userspace if it did not fit Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Reviewed-by: Christian Schoenebeck <linux_oss@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20221118135542.63400-1-asmadeus@xxxxxxxxxxxxx Signed-off-by: Dominique Martinet <asmadeus@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index ac60ddfcd88b..6459c2356ff9 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -230,6 +230,14 @@ static void p9_xen_response(struct work_struct *work) continue; } + if (h.size > req->rc.capacity) { + dev_warn(&priv->dev->dev, + "requested packet size too big: %d for tag %d with capacity %zd\n", + h.size, h.tag, req->rc.capacity); + req->status = REQ_STATUS_ERROR; + goto recv_error; + } + memcpy(&req->rc, &h, sizeof(h)); req->rc.offset = 0; @@ -239,6 +247,7 @@ static void p9_xen_response(struct work_struct *work) masked_prod, &masked_cons, XEN_9PFS_RING_SIZE); +recv_error: virt_mb(); cons += h.size; ring->intf->in_cons = cons;