From: arighi <arighi@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Wed, 3 Nov 2010 09:46:51 +0000 (+0000)
Subject: AT91SAM7X: gracefully drop bad frames read from the EMAC
X-Git-Tag: 2.6.0~5^2~26
X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=1cc52b017c6213f9e52e678d176b9eeaf2a892ca;p=bertos.git

AT91SAM7X: gracefully drop bad frames read from the EMAC

When a host in the same subnet changes their IP / mac address
association, we could have some "deprecated" frames in the ethernet
buffer.

The hardware seems to explicitly mark them, cleaning the ownership bit.
If this happens simply drop the frame and do not pass it to the upper
layers.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@4494 38d2e660-2303-0410-9eaa-f027e97ec537
---

diff --git a/bertos/cpu/arm/drv/eth_at91.c b/bertos/cpu/arm/drv/eth_at91.c
index 5d365b20..529d7af4 100644
--- a/bertos/cpu/arm/drv/eth_at91.c
+++ b/bertos/cpu/arm/drv/eth_at91.c
@@ -425,7 +425,11 @@ ssize_t eth_getFrame(uint8_t *buf, size_t len)
 			rd_len += EMAC_RX_BUFSIZ;
 		else
 			rd_len += len - rd_len;
-		ASSERT(rx_buf_tab[rx_buf_idx].addr & RXBUF_OWNERSHIP);
+		if (UNLIKELY(!(rx_buf_tab[rx_buf_idx].addr & RXBUF_OWNERSHIP)))
+		{
+			LOG_INFO("bad frame found\n");
+			return 0;
+		}
 		rx_buf_tab[rx_buf_idx].addr &= ~RXBUF_OWNERSHIP;
 		if (++rx_buf_idx >= EMAC_RX_DESCRIPTORS)
 			rx_buf_idx = 0;