[PATCH] examples/l3fwd: resolve stack buffer overflow issue

[Rahul Bhansali <rbhansali@marvell.com>]

This patch fixes the stack buffer overflow error reported
from AddressSanitizer.
Function send_packetsx4() tries to access out of bound data
from rte_mbuf and fill it into TX buffer even in the case
where no pending packets (len = 0).
Performance impact:- No

ASAN error report:-
==819==ERROR: AddressSanitizer: stack-buffer-overflow on address
0xffffe2c0dcf0 at pc 0x0000005e791c bp 0xffffe2c0d7e0 sp 0xffffe2c0d800
READ of size 8 at 0xffffe2c0dcf0 thread T0
 #0 0x5e7918 in send_packetsx4 ../examples/l3fwd/l3fwd_common.h:251
 #1 0x5e7918 in send_packets_multi ../examples/l3fwd/l3fwd_neon.h:226

Signed-off-by: Rahul Bhansali <rbhansali@marvell.com>
---
 examples/l3fwd/l3fwd_common.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/examples/l3fwd/l3fwd_common.h b/examples/l3fwd/l3fwd_common.h
index 7d83ff641a..de77711f88 100644
--- a/examples/l3fwd/l3fwd_common.h
+++ b/examples/l3fwd/l3fwd_common.h
@@ -236,6 +236,9 @@ send_packetsx4(struct lcore_conf *qconf, uint16_t port, struct rte_mbuf *m[],
 
 		/* copy rest of the packets into the TX buffer. */
 		len = num - n;
+		if (len == 0)
+			goto exit;
+
 		j = 0;
 		switch (len % FWDSTEP) {
 		while (j < len) {
@@ -258,6 +261,7 @@ send_packetsx4(struct lcore_conf *qconf, uint16_t port, struct rte_mbuf *m[],
 		}
 	}
 
+exit:
 	qconf->tx_mbufs[port].len = len;
 }
 
-- 
2.25.1