fixes for 4.19

[thirdparty/kernel/stable-queue.git] / releases / 3.0.1 / ethtool-allow-zero-length-register-dumps-again.patch

From 67ae7cf1eeda777f79259c4c6cb17a0bd28dee71 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <bhutchings@solarflare.com>
Date: Thu, 21 Jul 2011 15:25:30 -0700
Subject: ethtool: Allow zero-length register dumps again

From: Ben Hutchings <bhutchings@solarflare.com>

commit 67ae7cf1eeda777f79259c4c6cb17a0bd28dee71 upstream.

Some drivers (ab)use the ethtool_ops::get_regs operation to expose
only a hardware revision ID.  Commit
a77f5db361ed9953b5b749353ea2c7fed2bf8d93 ('ethtool: Allocate register
dump buffer with vmalloc()') had the side-effect of breaking these, as
vmalloc() returns a null pointer for size=0 whereas kmalloc() did not.

For backward-compatibility, allow zero-length dumps again.

Reported-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 net/core/ethtool.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1227,7 +1227,7 @@ static int ethtool_get_regs(struct net_d
 		regs.len = reglen;
 
 	regbuf = vzalloc(reglen);
-	if (!regbuf)
+	if (reglen && !regbuf)
 		return -ENOMEM;
 
 	ops->get_regs(dev, &regs, regbuf);
@@ -1236,7 +1236,7 @@ static int ethtool_get_regs(struct net_d
 	if (copy_to_user(useraddr, &regs, sizeof(regs)))
 		goto out;
 	useraddr += offsetof(struct ethtool_regs, data);
-	if (copy_to_user(useraddr, regbuf, regs.len))
+	if (regbuf && copy_to_user(useraddr, regbuf, regs.len))
 		goto out;
 	ret = 0;