3 files changed, 39 insertions, 0 deletions

diff --git a/lib/libc/stdio/fdopen.c b/lib/libc/stdio/fdopen.c
index c199871..02378ed 100644
--- a/lib/libc/stdio/fdopen.c
+++ b/lib/libc/stdio/fdopen.c
@@ -57,6 +57,18 @@ fdopen(fd, mode)
 	if (nofile == 0)
 		nofile = getdtablesize();
 
+	/*
+	 * File descriptors are a full int, but _file is only a short.
+	 * If we get a valid file descriptor that is greater than
+	 * SHRT_MAX, then the fd will get sign-extended into an
+	 * invalid file descriptor.  Handle this case by failing the
+	 * open.
+	 */
+	if (fd > SHRT_MAX) {
+		errno = EMFILE;
+		return (NULL);
+	}
+
 	if ((flags = __sflags(mode, &oflags)) == 0)
 		return (NULL);
 
diff --git a/lib/libc/stdio/fopen.c b/lib/libc/stdio/fopen.c
index 9cedcda..a6c0028 100644
--- a/lib/libc/stdio/fopen.c
+++ b/lib/libc/stdio/fopen.c
@@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
 #include "un-namespace.h"
@@ -63,6 +64,18 @@ fopen(file, mode)
 		fp->_flags = 0;			/* release */
 		return (NULL);
 	}
+	/*
+	 * File descriptors are a full int, but _file is only a short.
+	 * If we get a valid file descriptor that is greater than
+	 * SHRT_MAX, then the fd will get sign-extended into an
+	 * invalid file descriptor.  Handle this case by failing the
+	 * open.
+	 */
+	if (f > SHRT_MAX) {
+		_close(f);
+		errno = EMFILE;
+		return (NULL);
+	}
 	fp->_file = f;
 	fp->_flags = flags;
 	fp->_cookie = fp;
diff --git a/lib/libc/stdio/freopen.c b/lib/libc/stdio/freopen.c
index b5bc884..a566386 100644
--- a/lib/libc/stdio/freopen.c
+++ b/lib/libc/stdio/freopen.c
@@ -203,6 +203,20 @@ finish:
 		}
 	}
 
+	/*
+	 * File descriptors are a full int, but _file is only a short.
+	 * If we get a valid file descriptor that is greater than
+	 * SHRT_MAX, then the fd will get sign-extended into an
+	 * invalid file descriptor.  Handle this case by failing the
+	 * open.
+	 */
+	if (f > SHRT_MAX) {
+		fp->_flags = 0;		/* set it free */
+		FUNLOCKFILE(fp);
+		errno = EMFILE;
+		return (NULL);
+	}
+
 	fp->_flags = flags;
 	fp->_file = f;
 	fp->_cookie = fp;