randr: first check pScrPriv before using the pointer at RRFirstOutput

Fix a seg fault in case pScrPriv is NULL at ProcRRGetScreenInfo,
which later calls RRFirstOutput.

Signed-off-by: Ricardo Salveti de Araujo <ricardo.salveti@linaro.org>
Reviewed-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/randr/randr.c b/randr/randr.c
index 4d4298af9..103da48d7 100644
--- a/randr/randr.c
+++ b/randr/randr.c
@@ -446,6 +446,9 @@ RRFirstOutput(ScreenPtr pScreen)
     RROutputPtr output;
     int i, j;
 
+    if (!pScrPriv)
+        return NULL;
+
     if (pScrPriv->primaryOutput && pScrPriv->primaryOutput->crtc)
         return pScrPriv->primaryOutput;