stat() before open() because opening of special files may be harmful.

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/libc/gen/opendir.c b/lib/libc/gen/opendir.c
index b3c0e09..8cba9cf 100644
--- a/lib/libc/gen/opendir.c
+++ b/lib/libc/gen/opendir.c
@@ -56,6 +56,16 @@ opendir(name)
 	int saved_errno;
 	struct stat sb;
 
+	/*
+	 * stat() before open() because opening of special files may be
+	 * harmful.  fstat() after open because the file may have changed.
+	 */
+	if (stat(name, &sb) != 0)
+		return NULL;
+	if (!S_ISDIR(sb.st_mode)) {
+		errno = ENOTDIR;
+		return NULL;
+	}
 	if ((fd = open(name, O_RDONLY | O_NONBLOCK)) == -1)
 		return NULL;
 	dirp = NULL;