diff options
authorNeil Horman <nhorman@tuxdriver.com>2009-06-02 01:29:58 -0700
committerDavid S. Miller <davem@davemloft.net>2009-06-02 01:29:58 -0700
commitea30e11970a96cfe5e32c03a29332554573b4a10 (patch)
parent5a9a8e32ebe269c71d8d3e78f9435fe7729f38e9 (diff)
e1000: add missing length check to e1000 receive routine
Patch to fix bad length checking in e1000. E1000 by default does two things: 1) Spans rx descriptors for packets that don't fit into 1 skb on recieve 2) Strips the crc from a frame by subtracting 4 bytes from the length prior to doing an skb_put Since the e1000 driver isn't written to support receiving packets that span multiple rx buffers, it checks the End of Packet bit of every frame, and discards it if its not set. This places us in a situation where, if we have a spanning packet, the first part is discarded, but the second part is not (since it is the end of packet, and it passes the EOP bit test). If the second part of the frame is small (4 bytes or less), we subtract 4 from it to remove its crc, underflow the length, and wind up in skb_over_panic, when we try to skb_put a huge number of bytes into the skb. This amounts to a remote DOS attack through careful selection of frame size in relation to interface MTU. The fix for this is already in the e1000e driver, as well as the e1000 sourceforge driver, but no one ever pushed it to e1000. This is lifted straight from e1000e, and prevents small frames from causing the underflow described above Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Tested-by: Andy Gospodarek <andy@greyhouse.net> Signed-off-by: David S. Miller <davem@davemloft.net>
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index b1419e21b46b..fffb006b7d95 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -4027,8 +4027,9 @@ static bool e1000_clean_rx_irq(struct e1000_adapter *adapter,
length = le16_to_cpu(rx_desc->length);
- if (unlikely(!(status & E1000_RXD_STAT_EOP))) {
+ /* !EOP means multiple descriptors were used to store a single
+ * packet, also make sure the frame isn't just CRC only */
+ if (unlikely(!(status & E1000_RXD_STAT_EOP) || (length <= 4))) {
/* All receives must fit into a single buffer */
E1000_DBG("%s: Receive packet consumed multiple"
" buffers\n", netdev->name);