e1000e: enhance frame fragment detection

Originally patched by Neil Horman <nhorman@tuxdriver.com>

e1000e could with a jumbo frame enabled interface, and packet split disabled,
receive a packet that would overflow a single rx buffer.  While in practice
very hard to craft a packet that could abuse this, it is possible.

this is related to CVE-2009-4538

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
index d6ee28f6ea089efba9dee089b7b51daf9ef43058..d236efaf74781d68fd41c34d591c066ee063909b 100644 (file)
--- a/drivers/net/e1000e/e1000.h
+++ b/drivers/net/e1000e/e1000.h
@@ -421,6 +421,7 @@ struct e1000_info {
 /* CRC Stripping defines */
 #define FLAG2_CRC_STRIPPING               (1 << 0)
 #define FLAG2_HAS_PHY_WAKEUP              (1 << 1)
+#define FLAG2_IS_DISCARDING               (1 << 2)
 
 #define E1000_RX_DESC_PS(R, i)     \
        (&(((union e1000_rx_desc_packet_split *)((R).desc))[i]))

diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
index f91f247ed6afa70fbbbe3d5b05d383f74b58bc86..1ea395b6c992683c3bb4328548cc7da15e6a6223 100644 (file)
--- a/drivers/net/e1000e/netdev.c
+++ b/drivers/net/e1000e/netdev.c
@@ -450,13 +450,23 @@ static bool e1000_clean_rx_irq(struct e1000_adapter *adapter,
 
                length = le16_to_cpu(rx_desc->length);
 
-               /* !EOP means multiple descriptors were used to store a single
-                * packet, also make sure the frame isn't just CRC only */
-               if (!(status & E1000_RXD_STAT_EOP) || (length <= 4)) {
+               /*
+                * !EOP means multiple descriptors were used to store a single
+                * packet, if that's the case we need to toss it.  In fact, we
+                * need to toss every packet with the EOP bit clear and the
+                * next frame that _does_ have the EOP bit set, as it is by
+                * definition only a frame fragment
+                */
+               if (unlikely(!(status & E1000_RXD_STAT_EOP)))
+                       adapter->flags2 |= FLAG2_IS_DISCARDING;
+
+               if (adapter->flags2 & FLAG2_IS_DISCARDING) {
                        /* All receives must fit into a single buffer */
                        e_dbg("Receive packet consumed multiple buffers\n");
                        /* recycle */
                        buffer_info->skb = skb;
+                       if (status & E1000_RXD_STAT_EOP)
+                               adapter->flags2 &= ~FLAG2_IS_DISCARDING;
                        goto next_desc;
                }
 
@@ -745,10 +755,16 @@ static bool e1000_clean_rx_irq_ps(struct e1000_adapter *adapter,
                                 PCI_DMA_FROMDEVICE);
                buffer_info->dma = 0;
 
-               if (!(staterr & E1000_RXD_STAT_EOP)) {
+               /* see !EOP comment in other rx routine */
+               if (!(staterr & E1000_RXD_STAT_EOP))
+                       adapter->flags2 |= FLAG2_IS_DISCARDING;
+
+               if (adapter->flags2 & FLAG2_IS_DISCARDING) {
                        e_dbg("Packet Split buffers didn't pick up the full "
                              "packet\n");
                        dev_kfree_skb_irq(skb);
+                       if (staterr & E1000_RXD_STAT_EOP)
+                               adapter->flags2 &= ~FLAG2_IS_DISCARDING;
                        goto next_desc;
                }
 
@@ -1118,6 +1134,7 @@ static void e1000_clean_rx_ring(struct e1000_adapter *adapter)
 
        rx_ring->next_to_clean = 0;
        rx_ring->next_to_use = 0;
+       adapter->flags2 &= ~FLAG2_IS_DISCARDING;
 
        writel(0, adapter->hw.hw_addr + rx_ring->head);
        writel(0, adapter->hw.hw_addr + rx_ring->tail);