From 3a4d59e5cb35cf2395cfd8004dd16d45dd889e11 Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Thu, 5 Dec 2019 16:35:51 +0100
Subject: [PATCH] extensions: among: Check call to fstat()
If this fails, a bogus length value may be passed to mmap().
Fixes: 26753888720d8 ("nft: bridge: Rudimental among extension support")
(cherry picked from commit 25b38bcbf2fdc019f438805c7d1ecd877af9c968)
Signed-off-by: Phil Sutter <psutter@redhat.com>
---
extensions/libebt_among.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/extensions/libebt_among.c b/extensions/libebt_among.c
index 2e87db3bc06fa..715d559f432c2 100644
--- a/extensions/libebt_among.c
+++ b/extensions/libebt_among.c
@@ -6,6 +6,7 @@
* August, 2003
*/
+#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <getopt.h>
@@ -137,7 +138,10 @@ static int bramong_parse(int c, char **argv, int invert,
if ((fd = open(optarg, O_RDONLY)) == -1)
xtables_error(PARAMETER_PROBLEM,
"Couldn't open file '%s'", optarg);
- fstat(fd, &stats);
+ if (fstat(fd, &stats) < 0)
+ xtables_error(PARAMETER_PROBLEM,
+ "fstat(%s) failed: '%s'",
+ optarg, strerror(errno));
flen = stats.st_size;
/* use mmap because the file will probably be big */
optarg = mmap(0, flen, PROT_READ | PROT_WRITE,
--
2.24.0