From:   Tedd Ho-Jeong An <hj.tedd.an@gmail.com>
To:     linux-bluetooth@vger.kernel.org
Subject: [BlueZ PATCH 3/5] tools/btgatt-server: Replace random number generation function
Date:   Tue,  7 Dec 2021 16:54:44 -0800
Message-Id: <20211208005446.196637-4-hj.tedd.an@gmail.com>
In-Reply-To: <20211208005446.196637-1-hj.tedd.an@gmail.com>
References: <20211208005446.196637-1-hj.tedd.an@gmail.com>
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From: Tedd Ho-Jeong An <tedd.an@intel.com>

This patch replaces the rand() function to the l_getrandom() from ELL,
which uses the getrandom() system call.

It was reported by the Coverity scan
  rand() should not be used for security-related applications, because
  linear congruential algorithms are too easy to break
---
 Makefile.tools        | 4 ++--
 tools/btgatt-server.c | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/Makefile.tools b/Makefile.tools
index 63b52c386..45470b767 100644
--- a/Makefile.tools
+++ b/Makefile.tools
@@ -287,8 +287,8 @@ tools_btgatt_client_LDADD = src/libshared-mainloop.la \
 
 tools_btgatt_server_SOURCES = tools/btgatt-server.c src/uuid-helper.c
 tools_btgatt_server_LDADD = src/libshared-mainloop.la \
-						lib/libbluetooth-internal.la
-
+				lib/libbluetooth-internal.la \
+				src/libshared-ell.la $(ell_ldadd)
 tools_rctest_LDADD = lib/libbluetooth-internal.la
 
 tools_l2test_LDADD = lib/libbluetooth-internal.la
diff --git a/tools/btgatt-server.c b/tools/btgatt-server.c
index 000145a3d..d2a877275 100644
--- a/tools/btgatt-server.c
+++ b/tools/btgatt-server.c
@@ -20,6 +20,7 @@
 #include <getopt.h>
 #include <unistd.h>
 #include <errno.h>
+#include <ell/ell.h>
 
 #include "lib/bluetooth.h"
 #include "lib/hci.h"
@@ -286,7 +287,7 @@ static bool hr_msrmt_cb(void *user_data)
 	uint32_t cur_ee;
 
 	pdu[0] = 0x06;
-	pdu[1] = 90 + (rand() % 40);
+	pdu[1] = 90 + (l_getrandom_uint32() % 40);
 
 	if (expended_present) {
 		pdu[0] |= 0x08;
-- 
2.25.1