[PATCH V1 0/1] net: cdc_ncm: Fix TX zero padding

From: Jim Baxter
Date: Thu May 04 2017 - 15:41:51 EST


The zero padding that is added to NTB's does not zero
the memory correctly.
This happens because the skb_put called within the memset in
the line:
memset(skb_put(skb_out, ctx->tx_max - skb_out->len),
0, ctx->tx_max - skb_out->len);
causes the value of skb_out->len to be modified during
the two uses of it within the above line.
This causes non-zeroed data at the end of skb_out.

This issue was found when connecting between an ARM
Sabre SD Host platform and a test box that was
dropping the NDP's due to the non zeroed memory being
identified as an error.


To resolve this I have cached the value of
ctx->tx_max - skb_out->len before the memset operation.

Jim Baxter (1):
net: cdc_ncm: Fix TX zero padding

drivers/net/usb/cdc_ncm.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)