From 94caafa040e4b4289c968cd70d53041b1463ac4d Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu, 11 Mar 2021 08:21:06 -0300
Subject: io: Return EBAFD for negative file descriptor on fstat (BZ #27559)

Now that fstat is implemented on top fstatat we need to handle negative
inputs.  The implementation now rejects AT_FDCWD, which would otherwise
be accepted by the kernel.

Checked on x86_64-linux-gnu and on i686-linux-gnu.
---
 io/fstat.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'io/fstat.c')

diff --git a/io/fstat.c b/io/fstat.c
index dc11736..17f31bf 100644
--- a/io/fstat.c
+++ b/io/fstat.c
@@ -16,10 +16,16 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <sys/stat.h>
+#include <errno.h>
 
 int
 __fstat (int fd, struct stat *buf)
 {
+  if (fd < 0)
+    {
+      __set_errno (EBADF);
+      return -1;
+    }
   return __fstatat (fd, "", buf, AT_EMPTY_PATH);
 }
 
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