Re: [PATCH 21/28] net/hyperv: avoid uninitialized variable

[David Miller]

From: Arnd Bergmann 
Date: Tue, 18 Oct 2016 00:16:09 +0200

> The hdr_offset variable is only if we deal with a TCP or UDP packet,
> but as the check surrounding its usage tests for skb_is_gso()
> instead, the compiler has no idea if the variable is initialized
> or not at that point:
> 
> drivers/net/hyperv/netvsc_drv.c: In function ‘netvsc_start_xmit’:
> drivers/net/hyperv/netvsc_drv.c:494:42: error: ‘hdr_offset’ may be used 
> uninitialized in this function [-Werror=maybe-uninitialized]
> 
> This adds an additional check for the transport type, which
> tells the compiler that this path cannot happen. Since the
> get_net_transport_info() function should always be inlined
> here, I don't expect this to result in additional runtime
> checks.
> 
> Signed-off-by: Arnd Bergmann 

Applied.

[PATCH 21/28] net/hyperv: avoid uninitialized variable

[Arnd Bergmann]

The hdr_offset variable is only if we deal with a TCP or UDP packet,
but as the check surrounding its usage tests for skb_is_gso()
instead, the compiler has no idea if the variable is initialized
or not at that point:

drivers/net/hyperv/netvsc_drv.c: In function ‘netvsc_start_xmit’:
drivers/net/hyperv/netvsc_drv.c:494:42: error: ‘hdr_offset’ may be used 
uninitialized in this function [-Werror=maybe-uninitialized]

This adds an additional check for the transport type, which
tells the compiler that this path cannot happen. Since the
get_net_transport_info() function should always be inlined
here, I don't expect this to result in additional runtime
checks.

Signed-off-by: Arnd Bergmann 
---
 drivers/net/hyperv/netvsc_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index f0919bd..5d6e75a 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -447,7 +447,7 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct 
net_device *net)
 * Setup the sendside checksum offload only if this is not a
 * GSO packet.
 */
-   if (skb_is_gso(skb)) {
+   if ((net_trans_info & (INFO_TCP | INFO_UDP)) && skb_is_gso(skb)) {
struct ndis_tcp_lso_info *lso_info;
 
rndis_msg_size += NDIS_LSO_PPI_SIZE;
-- 
2.9.0