From ede56038e50235cd1ca7de3602c9491d3b84b49b Mon Sep 17 00:00:00 2001
From: Joseph Myers <[email protected]>
Date: Thu, 9 Jul 2020 21:51:49 +0000
Subject: [PATCH] Fix double free in __printf_fp_l (bug 26214).

__printf_fp_l has a double free bug in the case where it allocates
memory with malloc internally, then has an I/O error while outputting
trailing padding and tries to free that already-freed memory when the
error occurs.  This patch fixes this by setting the relevant pointer
to NULL after the first free (the only free of this pointer that isn't
immediately followed by returning from the function).

note that this patch is parts of the origin one.

Tested for x86_64 and x86.
---
 stdio-common/printf_fp.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/stdio-common/printf_fp.c b/stdio-common/printf_fp.c
index 66ab59ba..c310eb8e 100644
--- a/stdio-common/printf_fp.c
+++ b/stdio-common/printf_fp.c
@@ -1250,6 +1250,9 @@ __printf_fp_l (FILE *fp, locale_t loc,
 	{
 	  free (buffer);
 	  free (wbuffer);
+	  /* Avoid a double free if the subsequent PADN encounters an
+	     I/O error.  */
+	  wbuffer = NULL;
 	}
     }
 
-- 
2.23.0