netdev - [PATCH iproute2 5/5] namespace: limit length of network namespace

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Message-Id: <20180319165638.30166-6-stephen@networkplumber.org>
Date:   Mon, 19 Mar 2018 09:56:38 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     netdev@...r.kernel.org
Cc:     Stephen Hemminger <stephen@...workplumber.org>
Subject: [PATCH iproute2 5/5] namespace: limit length of network namespace

Avoid running into buffer overflows with excessively long network
namespace. Fixes Gcc-8 warning about possible snprintf truncation.

Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
---
 lib/namespace.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/namespace.c b/lib/namespace.c
index 682634028587..ce5683a5f4e6 100644
--- a/lib/namespace.c
+++ b/lib/namespace.c
@@ -18,7 +18,7 @@
 static void bind_etc(const char *name)
 {
 	char etc_netns_path[PATH_MAX];
-	char netns_name[PATH_MAX];
+	char netns_name[2*PATH_MAX];
 	char etc_name[PATH_MAX];
 	struct dirent *entry;
 	DIR *dir;
@@ -52,6 +52,12 @@ int netns_switch(char *name)
 	unsigned long mountflags = 0;
 	struct statvfs fsstat;
 
+	if (strlen(name) >= NAME_MAX) {
+		fprintf(stderr, "Network namespace name too long\"%s\"\n",
+			name);
+		return -1;
+	}
+
 	snprintf(net_path, sizeof(net_path), "%s/%s", NETNS_RUN_DIR, name);
 	netns = open(net_path, O_RDONLY | O_CLOEXEC);
 	if (netns < 0) {
-- 
2.16.2