From 223a960c01227e4dbcb6f9fa06b47d73bda21274 Mon Sep 17 00:00:00 2001 From: Aaro Koskinen Date: Mon, 18 Mar 2019 23:36:08 +0200 Subject: [PATCH] net: stmmac: fix memory corruption with large MTUs When using 16K DMA buffers and ring mode, the DES3 refill is not working correctly as the function is using a bogus pointer for checking the private data. As a result stale pointers will remain in the RX descriptor ring, so DMA will now likely overwrite/corrupt some already freed memory. As simple reproducer, just receive some UDP traffic: # ifconfig eth0 down; ifconfig eth0 mtu 9000; ifconfig eth0 up # iperf3 -c 192.168.253.40 -u -b 0 -R If you didn't crash by now check the RX descriptors to find non-contiguous RX buffers: cat /sys/kernel/debug/stmmaceth/eth0/descriptors_status [...] 1 [0x2be5020]: 0xa3220321 0x9ffc1ffc 0x72d70082 0x130e207e ^^^^^^^^^^^^^^^^^^^^^ 2 [0x2be5040]: 0xa3220321 0x9ffc1ffc 0x72998082 0x1311a07e ^^^^^^^^^^^^^^^^^^^^^ A simple ping test will now report bad data: # ping -s 8200 192.168.253.40 PING 192.168.253.40 (192.168.253.40) 8200(8228) bytes of data. 8208 bytes from 192.168.253.40: icmp_seq=1 ttl=64 time=1.00 ms wrong data byte #8144 should be 0xd0 but was 0x88 Fix the wrong pointer. Also we must refill DES3 only if the DMA buffer size is 16K. Fixes: 54139cf3bb33 ("net: stmmac: adding multiple buffers for rx") Signed-off-by: Aaro Koskinen Acked-by: Jose Abreu Signed-off-by: David S. Miller --- drivers/net/ethernet/stmicro/stmmac/ring_mode.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c index f936166d8910..4d9bcb4d0378 100644 --- a/drivers/net/ethernet/stmicro/stmmac/ring_mode.c +++ b/drivers/net/ethernet/stmicro/stmmac/ring_mode.c @@ -113,10 +113,11 @@ static unsigned int is_jumbo_frm(int len, int enh_desc) static void refill_desc3(void *priv_ptr, struct dma_desc *p) { - struct stmmac_priv *priv = (struct stmmac_priv *)priv_ptr; + struct stmmac_rx_queue *rx_q = priv_ptr; + struct stmmac_priv *priv = rx_q->priv_data; /* Fill DES3 in case of RING mode */ - if (priv->dma_buf_sz >= BUF_SIZE_8KiB) + if (priv->dma_buf_sz == BUF_SIZE_16KiB) p->des3 = cpu_to_le32(le32_to_cpu(p->des2) + BUF_SIZE_8KiB); } -- 2.30.2