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net: ethernet: dec: tulip: Fix length mask in receive length calculation

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The receive frame length calculation uses a wrong mask to calculate the
length of the received frames.

Per spec table 4-1 the length is contained in the FL (Frame Length)
field in bits 30:16.

This didn't show up as an issue so far since frames were limited to
1500 bytes which falls within the 11 bit window.

Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Moritz Fischer
2020-02-04 15:01:18 -08:00
committed by David S. Miller
parent 7bb77d4b85
commit 33e2b32b5d
1 changed files with 4 additions and 1 deletions
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5
drivers/net/ethernet/dec/tulip/de2104x.c
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@@ -417,7 +417,10 @@ static void de_rx (struct de_private *de)
if (status & DescOwn) if (status & DescOwn)
break; break;
len = ((status >> 16) & 0x7ff) - 4; /* the length is actually a 15 bit value here according
* to Table 4-1 in the DE2104x spec so mask is 0x7fff
*/
len = ((status >> 16) & 0x7fff) - 4;
mapping = de->rx_skb[rx_tail].mapping; mapping = de->rx_skb[rx_tail].mapping;
if (unlikely(drop)) { if (unlikely(drop)) {