[PATCH] q_tbf: Fix potential static-overflow in tbf_print_opt

[Maks Mishin <maks.mishinfz@gmail.com>]

An element of array '&b1[0]' of size 64, declared at q_tbf.c:257,
is accessed by an index with values in [0, 74] at q_tbf.c:279,
which may lead to a buffer overflow.

Details: Format string: '%s/%u'. Size of buffer parameter is 63;
Specifier '%u': min value '-2147483647' requires 10 character(s),
max value '2147483647' requires 10 character(s), so the buffer needs
enough space to receive 10 character(s).
Size of the string except for specifiers is 1; Total maximum size is 74.

Found by RASU JSC.

Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>
---
 tc/q_tbf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tc/q_tbf.c b/tc/q_tbf.c
index 9356dfd2..b9f4191c 100644
--- a/tc/q_tbf.c
+++ b/tc/q_tbf.c
@@ -254,7 +254,7 @@ static int tbf_print_opt(const struct qdisc_util *qu, FILE *f, struct rtattr *op
 	double latency, lat2;
 	__u64 rate64 = 0, prate64 = 0;
 
-	SPRINT_BUF(b1);
+	char b1[74];
 	SPRINT_BUF(b2);
 	SPRINT_BUF(b3);
 
-- 
2.30.2