lib: Fix potential out of bounds access in ring stop code

The subsequet code expects the read() to not have filled the entire
buffer, and yet we allow it to do so. Reduce the size passed to read()
by 1 to make the code sane.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index 52b8e2fe..4fd2e5aa 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -666,7 +666,7 @@ enum stop_ring_flags igt_get_stop_rings(void)
 
 	fd = igt_debugfs_open("i915_ring_stop", O_RDONLY);
 	igt_assert(fd >= 0);
-	l =  read(fd, buf, sizeof(buf));
+	l = read(fd, buf, sizeof(buf)-1);
 	igt_assert(l > 0);
 	igt_assert(l < sizeof(buf));