[PATCH] ibmveth: Fix off-by-one error in ibmveth_change_mtu()
From: David Gibson <hidden>
Date: 2015-04-13 05:40:05
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Subsystem:
ibm power virtual ethernet device driver, linux for powerpc (32-bit and 64-bit), networking drivers, the rest · Maintainers:
Nick Child, Madhavan Srinivasan, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
AFAIK the PAPR document which defines the virtual device interface used by the ibmveth driver doesn't specify a specific maximum MTU. So, in the ibmveth driver, the maximum allowed MTU is determined by the maximum allocated buffer size of 64k (corresponding to one page in the common case) minus the per-buffer overhead IBMVETH_BUFF_OH (which has value 22 for 14 bytes of ethernet header, plus 8 bytes for an opaque handle). This suggests a maximum allowable MTU of 65514 bytes, but in fact the driver only permits a maximum MTU of 65513. This is because there is a < instead of an <= in ibmveth_change_mtu(), which only permits an MTU which is strictly smaller than the buffer size, rather than allowing the buffer to be completely filled. This patch fixes the buglet. Signed-off-by: David Gibson <redacted> --- drivers/net/ethernet/ibm/ibmveth.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index cd7675a..3aa280a 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c@@ -1257,7 +1257,7 @@ static int ibmveth_change_mtu(struct net_device *dev, int new_mtu) for (i = 0; i < IBMVETH_NUM_BUFF_POOLS; i++) { adapter->rx_buff_pool[i].active = 1; - if (new_mtu_oh < adapter->rx_buff_pool[i].buff_size) { + if (new_mtu_oh <= adapter->rx_buff_pool[i].buff_size) { dev->mtu = new_mtu; vio_cmo_set_dev_desired(viodev, ibmveth_get_desired_dma
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2.1.0