[Intel-gfx] [PATCH i-g-t rfc 01/29] lib/igt_debugfs: Prevent buffer overflow

[Robert Foss]

buf array may overflow with when writing '\0' if
MAX_LINE_LEN bytes are read during read().

Signed-off-by: Robert Foss <robert.foss at collabora.com>
---
 lib/igt_debugfs.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index d828687a..8b8a627a 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -594,13 +594,15 @@ static int read_crc(igt_pipe_crc_t *pipe_crc, igt_crc_t *out)
 		read_len = MAX_LINE_LEN;
 
 	igt_set_timeout(5, "CRC reading");
-	bytes_read = read(pipe_crc->crc_fd, &buf, read_len);
+	bytes_read = read(pipe_crc->crc_fd, &buf, read_len - 1);
 	igt_reset_timeout();
 
-	if (bytes_read < 0 && errno == EAGAIN) {
+	if (bytes_read < 0 && errno == EAGAIN)
 		igt_assert(pipe_crc->flags & O_NONBLOCK);
+
+	if (bytes_read < 0)
 		bytes_read = 0;
-	}
+
 	buf[bytes_read] = '\0';
 
 	if (bytes_read && !pipe_crc_init_from_string(pipe_crc, out, buf))
-- 
2.11.0