Hello,
we developing CDC/NCM firmware and found that the Linux CDC/NCM is not
compliant to the USB CDC/NCM specification. The cause is a Bug in the
cdc_ncm.c file.
The structure usb_cdc_ncm_ndp_input_size is only allocated but not
initialized. The CDC/NCM specification section "6.2.7 SetNtbInputSize"
says that the dwNtbInMaxSize field must be at least 2048. But the
current implementation leave it 0, because it is not initialized.
I'm not sure if it is also required to initialize the wNtbInMaxDatagrams
field because 0 (no limit) is a valid value.
--- linux-3.6-rc4.orig/drivers/net/usb/cdc_ncm.c 2012-09-06
14:05:26.981402153 +0200
+++ linux-3.6-rc4/drivers/net/usb/cdc_ncm.c 2012-09-06
14:11:57.137398615 +0200
@@ -224,6 +224,7 @@
err = -ENOMEM;
goto size_err;
}
+ ndp_in_sz->dwNtbInMaxSize = cpu_to_le32(ctx->rx_max);
err = usb_control_msg(ctx->udev,
usb_sndctrlpipe(ctx->udev, 0),
--
Kind regards,
Frank Hoffmann
Thesycon GmbH
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