[PATCH] net: ethtool: avoid allocation failure for dump_regs

[David Arcari <darcari@redhat.com>]

If the user executes 'ethtool -d' for an interface and the associated
get_regs_len() function returns 0, the user will see a call trace from
the vmalloc() call in ethtool_get_regs().  This patch modifies
ethtool_get_regs() to avoid the call to vmalloc when the size is zero.

Signed-off-by: David Arcari <darcari@redhat.com>
---
 net/core/ethtool.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index e23766c..47acd6f 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1405,7 +1405,7 @@ static int ethtool_get_regs(struct net_device *dev, char __user *useraddr)
 	if (regs.len > reglen)
 		regs.len = reglen;
 
-	regbuf = vzalloc(reglen);
+	regbuf = reglen ? vzalloc(reglen) : NULL;
 	if (reglen && !regbuf)
 		return -ENOMEM;