[patch linux-2.6.11-bk10 1/1] r8169: incoming frame length check

[Francois Romieu <romieu@xxxxxxxxxxxxx>]

The size of the incoming frame is not correctly checked.

The RxMaxSize register (0xDA) does not work as expected and incoming
frames whose size exceeds the MTU actually end spanning multiple
descriptors. The first Rx descriptor contains the size of the whole
frame (or some garbage in its place). The driver does not expect 
something above the space allocated to the current skb and crashes
loudly when it issues a skb_put.

The fix contains two parts:
- disable hardware Rx size filtering: so far it only proved to be able
  to trigger some new fancy errors;
- drop multi-descriptors frame: as the driver allocates MTU sized Rx
  buffers, it provides an adequate filtering.

As a bonus, wrong descriptors were not returned to the asic after their
processing.

Signed-off-by: Francois Romieu <romieu@xxxxxxxxxxxxx>

diff -puN drivers/net/r8169.c~r8169-570 drivers/net/r8169.c
--- linux-2.6.11/drivers/net/r8169.c~r8169-570  2005-03-13 23:35:37.000000000 
+0100
+++ linux-2.6.11-fr/drivers/net/r8169.c 2005-03-14 23:47:56.529014957 +0100
@@ -1585,8 +1585,8 @@ rtl8169_hw_start(struct net_device *dev)
        RTL_W8(ChipCmd, CmdTxEnb | CmdRxEnb);
        RTL_W8(EarlyTxThres, EarlyTxThld);
 
-       /* For gigabit rtl8169, MTU + header + CRC + VLAN */
-       RTL_W16(RxMaxSize, tp->rx_buf_sz);
+       /* Low hurts. Let's disable the filtering. */
+       RTL_W16(RxMaxSize, 16383);
 
        /* Set Rx Config register */
        i = rtl8169_rx_config |
@@ -2127,6 +2127,11 @@ rtl8169_tx_interrupt(struct net_device *
        }
 }
 
+static inline int rtl8169_fragmented_frame(u32 status)
+{
+       return (status & (FirstFrag | LastFrag)) != (FirstFrag | LastFrag);
+}
+
 static inline void rtl8169_rx_csum(struct sk_buff *skb, struct RxDesc *desc)
 {
        u32 opts1 = le32_to_cpu(desc->opts1);
@@ -2177,27 +2182,41 @@ rtl8169_rx_interrupt(struct net_device *
 
        while (rx_left > 0) {
                unsigned int entry = cur_rx % NUM_RX_DESC;
+               struct RxDesc *desc = tp->RxDescArray + entry;
                u32 status;
 
                rmb();
-               status = le32_to_cpu(tp->RxDescArray[entry].opts1);
+               status = le32_to_cpu(desc->opts1);
 
                if (status & DescOwn)
                        break;
                if (status & RxRES) {
-                       printk(KERN_INFO "%s: Rx ERROR!!!\n", dev->name);
+                       printk(KERN_INFO "%s: Rx ERROR. status = %08x\n",
+                              dev->name, status);
                        tp->stats.rx_errors++;
                        if (status & (RxRWT | RxRUNT))
                                tp->stats.rx_length_errors++;
                        if (status & RxCRC)
                                tp->stats.rx_crc_errors++;
+                       rtl8169_mark_to_asic(desc, tp->rx_buf_sz);
                } else {
-                       struct RxDesc *desc = tp->RxDescArray + entry;
                        struct sk_buff *skb = tp->Rx_skbuff[entry];
                        int pkt_size = (status & 0x00001FFF) - 4;
                        void (*pci_action)(struct pci_dev *, dma_addr_t,
                                size_t, int) = pci_dma_sync_single_for_device;
 
+                       /*
+                        * The driver does not support incoming fragmented
+                        * frames. They are seen as a symptom of over-mtu
+                        * sized frames.
+                        */
+                       if (unlikely(rtl8169_fragmented_frame(status))) {
+                               tp->stats.rx_dropped++;
+                               tp->stats.rx_length_errors++;
+                               rtl8169_mark_to_asic(desc, tp->rx_buf_sz);
+                               goto move_on;
+                       }
+
                        rtl8169_rx_csum(skb, desc);
                        
                        pci_dma_sync_single_for_cpu(tp->pci_dev,
@@ -2224,7 +2243,7 @@ rtl8169_rx_interrupt(struct net_device *
                        tp->stats.rx_bytes += pkt_size;
                        tp->stats.rx_packets++;
                }
-               
+move_on:               
                cur_rx++; 
                rx_left--;
        }

_