[PATCH] drivers/net/usb/r8152 fix broken rx checksums

[Mark Lord]

The r8152 driver has been broken since (approx) 3.6.16,
when support was added for hardware rx checksum on newer chip versions.
Symptoms include random segfaults and silent data corruption over NFS.

This does not work on the VER_02 dongle I have here
when used with a slow embedded system CPU.
Google reveals others reporting similar issues on Raspberry Pi.

So, disable hardware rx checksum for VER_02, and fix
an obvious coding error for IPV6 checksums in the same function.

Because this bug results in silent data corruption,
it is a good candidate for back-porting to -stable >= 3.16.xx.
Patch attached (to deal with buggy mailer) and also below for review.

Signed-off-by: Mark Lord <mlord@xxxxxxxxx>

--- old/drivers/net/usb/r8152.c	2016-09-30 04:20:43.000000000 -0400
+++ linux/drivers/net/usb/r8152.c	2016-10-26 14:15:44.932517676 -0400
@@ -1645,7 +1645,7 @@
 	u8 checksum = CHECKSUM_NONE;
 	u32 opts2, opts3;

-	if (tp->version == RTL_VER_01)
+	if (tp->version == RTL_VER_01 || tp->version == RTL_VER_02)
 		goto return_result;

 	opts2 = le32_to_cpu(rx_desc->opts2);
@@ -1660,7 +1660,7 @@
 			checksum = CHECKSUM_NONE;
 		else
 			checksum = CHECKSUM_UNNECESSARY;
-	} else if (RD_IPV6_CS) {
+	} else if (opts2 & RD_IPV6_CS) {
 		if ((opts2 & RD_UDP_CS) && !(opts3 & UDPF))
 			checksum = CHECKSUM_UNNECESSARY;
 		else if ((opts2 & RD_TCP_CS) && !(opts3 & TCPF))
The r8152 driver has been broken since (approx) 3.6.16,
when support was added for hardware rx checksum on newer chip versions.
Symptoms include random segfaults and silent data corruption over NFS.

This does not work on the VER_02 dongle I have here
when used with a slow embedded system CPU.
Google reveals others reporting similar issues on Raspberry Pi.

So, disable hardware rx checksum for VER_02, and fix
an obvious coding error for IPV6 checksums in the same function.

Because this bug results in silent data corruption,
it is a good candidate for back-porting to -stable >= 3.16.xx.

Signed-off-by: Mark Lord <mlord@xxxxxxxxx>

--- old/drivers/net/usb/r8152.c	2016-09-30 04:20:43.000000000 -0400
+++ linux/drivers/net/usb/r8152.c	2016-10-26 14:15:44.932517676 -0400
@@ -1645,7 +1645,7 @@
 	u8 checksum = CHECKSUM_NONE;
 	u32 opts2, opts3;
 
-	if (tp->version == RTL_VER_01)
+	if (tp->version == RTL_VER_01 || tp->version == RTL_VER_02)
 		goto return_result;
 
 	opts2 = le32_to_cpu(rx_desc->opts2);
@@ -1660,7 +1660,7 @@
 			checksum = CHECKSUM_NONE;
 		else
 			checksum = CHECKSUM_UNNECESSARY;
-	} else if (RD_IPV6_CS) {
+	} else if (opts2 & RD_IPV6_CS) {
 		if ((opts2 & RD_UDP_CS) && !(opts3 & UDPF))
 			checksum = CHECKSUM_UNNECESSARY;
 		else if ((opts2 & RD_TCP_CS) && !(opts3 & TCPF))