Commit e35c3ad0 authored Nov 18, 2022 by Dominique Martinet Committed by Greg Kroah-Hartman Dec 14, 2022

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@kernel.org>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Link: https://lkml.kernel.org/r/20221118135542.63400-1-asmadeus@codewreck.org


Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 9d5126b5

net/9p/trans_xen.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -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;