Commit f86c1d3f authored Mar 27, 2019 by Aaro Koskinen Committed by Greg Kroah-Hartman May 08, 2019

net: stmmac: fix dropping of multi-descriptor RX frames



[ Upstream commit 8ac0c24fe1c256af6644caf3d311029440ec2fbd ]

Packets without the last descriptor set should be dropped early. If we
receive a frame larger than the DMA buffer, the HW will continue using the
next descriptor. Driver mistakes these as individual frames, and sometimes
a truncated frame (without the LD set) may look like a valid packet.

This fixes a strange issue where the system replies to 4098-byte ping
although the MTU/DMA buffer size is set to 4096, and yet at the same
time it's logging an oversized packet.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 0ab012e3

drivers/net/ethernet/stmicro/stmmac/enh_desc.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -201,6 +201,11 @@ static int enh_desc_get_rx_status(void data, struct stmmac_extra_stats x,
		if (unlikely(rdes0 & RDES0_OWN))
		return dma_own;

		if (unlikely(!(rdes0 & RDES0_LAST_DESCRIPTOR))) {
		stats->rx_length_errors++;
		return discard_frame;
		}

		if (unlikely(rdes0 & RDES0_ERROR_SUMMARY)) {
		if (unlikely(rdes0 & RDES0_DESCRIPTOR_ERROR)) {
		x->rx_desc++;