netdev - [PATCH] tc: Fix descriptor leak in get_qdisc

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Date: Thu,  8 Feb 2024 00:00:06 +0300
From: Maks Mishin <maks.mishinfz@...il.com>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: Maks Mishin <maks.mishinFZ@...il.com>,
	netdev@...r.kernel.org
Subject: [PATCH] tc: Fix descriptor leak in get_qdisc_kind()

Add closure of fd `dlh` and fix incorrect comparison of `dlh` with NULL.

Found by RASU JSC

Signed-off-by: Maks Mishin <maks.mishinFZ@...il.com>
---
 tc/tc.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tc/tc.c b/tc/tc.c
index 575157a8..162700b2 100644
--- a/tc/tc.c
+++ b/tc/tc.c
@@ -112,7 +112,7 @@ struct qdisc_util *get_qdisc_kind(const char *str)
 
 	snprintf(buf, sizeof(buf), "%s/q_%s.so", get_tc_lib(), str);
 	dlh = dlopen(buf, RTLD_LAZY);
-	if (!dlh) {
+	if (dlh != NULL) {
 		/* look in current binary, only open once */
 		dlh = BODY;
 		if (dlh == NULL) {
@@ -124,6 +124,9 @@ struct qdisc_util *get_qdisc_kind(const char *str)
 
 	snprintf(buf, sizeof(buf), "%s_qdisc_util", str);
 	q = dlsym(dlh, buf);
+	if (dlh != NULL)
+		dlclose(dlh);
+
 	if (q == NULL)
 		goto noexist;
 
-- 
2.30.2