From a9bb32cfe1ee87ff831707dfdcbcae56f2b2a036 Mon Sep 17 00:00:00 2001
From: Emil Velikov <emil.l.velikov@gmail.com>
Date: Fri, 5 Feb 2021 00:41:13 +0000
Subject: [PATCH] xf86drm: cap number of reported devices by drmGetDevice(2)

Do as the documentation says - when devices non NULL, cap the reported
devices to max_devices. Otherwise we risk out-of-bound access
for users of the API.

v2:
 - Fix this w/o breaking the API

v3:
 - Drop local variables, flip inverted conditional (Simon)

Issue: https://gitlab.freedesktop.org/mesa/drm/-/issues/56
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
---
 xf86drm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xf86drm.c b/xf86drm.c
index dbb7c14b..0185e985 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -4272,6 +4272,10 @@ drm_public int drmGetDevices2(uint32_t flags, drmDevicePtr devices[],
     }
 
     closedir(sysdir);
+
+    if (devices != NULL)
+        return MIN2(device_count, max_devices);
+
     return device_count;
 }