Thread (13 messages) flat view 13 messages, 5 authors, 2016-10-27
STALE3605d

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

From: Arnd Bergmann <arnd@arndb.de>
Date: 2016-10-17 22:17:30
Also in: lkml
Subsystem: hyper-v/azure core and drivers, networking drivers, the rest · Maintainers: "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

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 <arnd@arndb.de>
---
 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

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