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USB: Fix CDC EEM host driver 'sentinel' CRC validation

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This is an alternate solution to the EEM 'sentinel' CRC valiation issue.

CDC EEM allows using a 'sentinel' ethernet frame CRC of 0xdeadbeef in
place of a real CRC.  The 'sentinel' value is transmitted in big-endian
order whereas the normal CRC is little-endian.  This patch handles both
cases appropriately.

Signed-off-by: Brian Niebuhr <bniebuhr@efjohnson.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Brian Niebuhr 2009-08-10 16:46:59 -05:00 committed by Greg Kroah-Hartman
parent 5429c73165
commit 9ca33a0f1a
1 changed files with 10 additions and 7 deletions
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17
drivers/net/usb/cdc_eem.c
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@ -300,20 +300,23 @@ static int eem_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
return 0;
}
crc = get_unaligned_le32(skb2->data
+ len - ETH_FCS_LEN);
skb_trim(skb2, len - ETH_FCS_LEN);
/*
* The bmCRC helps to denote when the CRC field in
* the Ethernet frame contains a calculated CRC:
* bmCRC = 1 : CRC is calculated
* bmCRC = 0 : CRC = 0xDEADBEEF
*/
if (header & BIT(14))
crc2 = ~crc32_le(~0, skb2->data, skb2->len);
else
if (header & BIT(14)) {
crc = get_unaligned_le32(skb2->data
+ len - ETH_FCS_LEN);
crc2 = ~crc32_le(~0, skb2->data, skb2->len
- ETH_FCS_LEN);
} else {
crc = get_unaligned_be32(skb2->data
+ len - ETH_FCS_LEN);
crc2 = 0xdeadbeef;
}
skb_trim(skb2, len - ETH_FCS_LEN);
if (is_last)
return crc == crc2;