netdev - [PATCH iproute2] color: handle case where fmt is NULL

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Message-ID: <20240123043010.266210-1-stephen@networkplumber.org>
Date: Mon, 22 Jan 2024 20:30:10 -0800
From: Stephen Hemminger <stephen@...workplumber.org>
To: netdev@...r.kernel.org
Cc: Stephen Hemminger <stephen@...workplumber.org>,
	Pedro Tammela <pctammela@...atatu.com>
Subject: [PATCH iproute2] color: handle case where fmt is NULL

There are cases where NULL is passed as format string when
nothing is to be printed. This is commonly done in the print_bool
function when a flag is false. Glibc seems to handle this case nicely
but for musl it will cause a segmentation fault

Since nothing needs to be printed, in this case; just check
for NULL and return.

Reported-by: Pedro Tammela <pctammela@...atatu.com>
Signed-off-by: Stephen Hemminger <stephen@...workplumber.org>
---
 lib/color.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/color.c b/lib/color.c
index 59976847295c..cd0f9f7509b5 100644
--- a/lib/color.c
+++ b/lib/color.c
@@ -140,6 +140,9 @@ int color_fprintf(FILE *fp, enum color_attr attr, const char *fmt, ...)
 	int ret = 0;
 	va_list args;
 
+	if (fmt == NULL)
+		return 0;
+
 	va_start(args, fmt);
 
 	if (!color_is_enabled || attr == COLOR_NONE) {
-- 
2.43.0