[PATCH v2] gpu: drm: drm_dp_mst_topology.c: Fix improper use of strncat - dri-devel - freedesktop.org experimental mailing list

11 Oct 2014

Fixed wrong usage of strncat, switched to strlcpy.
While sending the string size to function to reduce
the potential for misuse in future.
Signed-off-by: Rickard Strandqvist rickard_strandqvist@spectrumdigital.se
---
 drivers/gpu/drm/drm_dp_mst_topology.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index ac3c273..2a146d1 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -995,19 +995,20 @@ static void drm_dp_check_port_guid(struct drm_dp_mst_branch *mstb,
static void build_mst_prop_path(struct drm_dp_mst_port *port,
    			struct drm_dp_mst_branch *mstb,
-				char *proppath)
+				char *proppath,
+				size_t proppath_size)
 {
    int i;
    char temp[8];
-	snprintf(proppath, 255, "mst:%d", mstb->mgr->conn_base_id);
+	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
    for (i = 0; i < (mstb->lct - 1); i++) {
    	int shift = (i % 2) ? 0 : 4;
    	int port_num = mstb->rad[i / 2] >> shift;
-		snprintf(temp, 8, "-%d", port_num);
-		strncat(proppath, temp, 255);
+		snprintf(temp, sizeof(temp), "-%d", port_num);
+		strlcat(proppath, temp, proppath_size);
    }
-	snprintf(temp, 8, "-%d", port->port_num);
-	strncat(proppath, temp, 255);
+	snprintf(temp, sizeof(temp), "-%d", port->port_num);
+	strlcat(proppath, temp, proppath_size);
 }
static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
@@ -1078,7 +1079,7 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
if (created && !port->input) {
    	char proppath[255];
-		build_mst_prop_path(port, mstb, proppath);
+		build_mst_prop_path(port, mstb, proppath, sizeof(proppath));
    	port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
    }
-- 
1.7.10.4


    