render: Bounds check for nglyphs in ProcRenderAddGlyphs (#28801)

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Julien Cristau <jcristau@debian.org>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/render/render.c b/render/render.c
index ef233e498..00241f9af 100644
--- a/render/render.c
+++ b/render/render.c
@@ -1077,6 +1077,14 @@ ProcRenderAddGlyphs (ClientPtr client)
     gi = (xGlyphInfo *) (gids + nglyphs);
     bits = (CARD8 *) (gi + nglyphs);
     remain -= (sizeof (CARD32) + sizeof (xGlyphInfo)) * nglyphs;
+
+    /* protect against bad nglyphs */
+    if (gi < stuff || gi > ((CARD32 *)stuff + client->req_len) ||
+        bits < stuff || bits > ((CARD32 *)stuff + client->req_len)) {
+        err = BadLength;
+        goto bail;
+    }
+
     for (i = 0; i < nglyphs; i++)
     {
         size_t padded_width;