From e049c5fcce862e994fc1b79baf8671c0aa25894e Mon Sep 17 00:00:00 2001
From: Quentin Young <qlyoung@cumulusnetworks.com>
Date: Mon, 12 Mar 2018 14:01:47 -0400
Subject: [PATCH] lib: fixup zlog_hexdump

* Allocate correct amount of memory
* Use snprintf() instead of sprintf()

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
---
 lib/log.c | 41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/lib/log.c b/lib/log.c
index 9e33ef910..2d856cc77 100644
--- a/lib/log.c
+++ b/lib/log.c
@@ -1092,41 +1092,50 @@ void zlog_hexdump(const void *mem, unsigned int len)
 	unsigned long i = 0;
 	unsigned int j = 0;
 	unsigned int columns = 8;
-	char buf[(len * 4) + ((len / 4) * 20) + 30];
+	/* 19 bytes for 0xADDRESS: */
+	/* 24 bytes for data; 2 chars plus a space per data byte */
+	/*  1 byte for space */
+	/*  8 bytes for ASCII representation */
+	/*  1 byte for a newline */
+	/* ===================== */
+	/* 53 bytes per 8 bytes of data */
+	/*  1 byte for null term */
+	size_t bs = ((len / 8) + 1) * 53 + 1;
+	char buf[bs];
 	char *s = buf;
 
+	memset(buf, 0, sizeof(buf));
+
 	for (i = 0; i < len + ((len % columns) ? (columns - len % columns) : 0);
 	     i++) {
 		/* print offset */
 		if (i % columns == 0)
-			s += sprintf(s, "0x%016lx: ", (unsigned long)mem + i);
+			s += snprintf(s, bs - (s - buf),
+				      "0x%016lx: ", (unsigned long)mem + i);
 
 		/* print hex data */
 		if (i < len)
-			s += sprintf(s, "%02x ", 0xFF & ((const char *)mem)[i]);
+			s += snprintf(s, bs - (s - buf), "%02x ",
+				      0xFF & ((const char *)mem)[i]);
 
 		/* end of block, just aligning for ASCII dump */
 		else
-			s += sprintf(s, "   ");
+			s += snprintf(s, bs - (s - buf), "   ");
 
 		/* print ASCII dump */
 		if (i % columns == (columns - 1)) {
 			for (j = i - (columns - 1); j <= i; j++) {
-				if (j >= len) /* end of block, not really
-						 printing */
-					s += sprintf(s, " ");
-
-				else if (isprint((int)((const char *)mem)
-							 [j])) /* printable char
-								  */
-					s += sprintf(
-						s, "%c",
+				/* end of block not really printing */
+				if (j >= len)
+					s += snprintf(s, bs - (s - buf), " ");
+				else if (isprint((int)((const char *)mem)[j]))
+					s += snprintf(
+						s, bs - (s - buf), "%c",
 						0xFF & ((const char *)mem)[j]);
-
 				else /* other char */
-					s += sprintf(s, ".");
+					s += snprintf(s, bs - (s - buf), ".");
 			}
-			s += sprintf(s, "\n");
+			s += snprintf(s, bs - (s - buf), "\n");
 		}
 	}
 	zlog_debug("\n%s", buf);
-- 
2.39.5