[stable] [029/102] ethtool: Allow zero-length register dumps again

[Greg KH]

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Ben Hutchings <bhutchi...@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 <kv...@qca.qualcomm.com>
Signed-off-by: Ben Hutchings <bhutchi...@solarflare.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@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;
 


_______________________________________________
stable mailing list
stable@linux.kernel.org
http://linux.kernel.org/mailman/listinfo/stable