> -----邮件原件-----
> 发件人: Michal Kubecek [mailto:mkube...@suse.cz]
> 发送时间: 2019年3月28日 17:09
> 收件人: Li,Rongqing <lirongq...@baidu.com>
> 抄送: netdev@vger.kernel.org
> 主题: Re: [PATCH] net: ethtool: not call vzalloc for zero sized memory request
>
> On Thu, Mar 28, 2019 at 02:01:09PM +0800, Li RongQing wrote:
> > NULL or ZERO_SIZE_PTR will be returned for zero sized memory request,
> > and derefencing them will lead to a segfault
> >
> > so it is unnecessory to call vzalloc for zero sized memory request and
> > not call __ethtool_get_strings which always uses the allocated memory
> >
> > this also fixes a possible memory leak if phy_ethtool_get_stats
> > returns error, memory should be freed before exit
> >
> > Signed-off-by: Li RongQing <lirongq...@baidu.com>
> > Reviewed-by: Wang Li <wangl...@baidu.com>
> > ---
> > net/core/ethtool.c | 37 ++++++++++++++++++++++++++-----------
> > 1 file changed, 26 insertions(+), 11 deletions(-)
> >
> > diff --git a/net/core/ethtool.c b/net/core/ethtool.c index
> > b1eb32419732..3e971a36e37c 100644
> > --- a/net/core/ethtool.c
> > +++ b/net/core/ethtool.c
> ...
> > @@ -1897,9 +1902,14 @@ static int ethtool_get_stats(struct net_device
> *dev, void __user *useraddr)
> > return -EFAULT;
> >
> > stats.n_stats = n_stats;
> > - data = vzalloc(array_size(n_stats, sizeof(u64)));
> > - if (n_stats && !data)
> > - return -ENOMEM;
> > +
> > + if (n_stats) {
> > + data = vzalloc(array_size(n_stats, sizeof(u64)));
> > + if (!data)
> > + return -ENOMEM;
> > + } else {
> > + data = NULL;
> > + }
> >
> > ops->get_ethtool_stats(dev, &stats, data);
> >
>
> You avoid the vzalloc() call here but you still pass null data pointer to
> device's
> get_ethtool_stats() handler which seems to contradict what the commit
> message says. Is it really what you want? (The same applies to
> ethtool_get_phy_stats() below.)
>
I keep it deliberately
ops->get_ethtool_stats(dev, &stats, data) have three parameter,
if n_stats is 0 [we assume the returning 0 of ops->get_sset_count is correct,
or
get_sset_count should be fixed], data is NULL, get_ethtool_stats () maybe
still
store the data into its seconds parameter, stats, even if I did not find which
drivers
is like that
but __ethtool_get_strings is different, only one place to store data, so
if count is 0, __ethtool_get_strings does not need to be called
-RongQing
> Michal
>
> > @@ -1941,14 +1951,19 @@ static int ethtool_get_phy_stats(struct
> net_device *dev, void __user *useraddr)
> > return -EFAULT;
> >
> > stats.n_stats = n_stats;
> > - data = vzalloc(array_size(n_stats, sizeof(u64)));
> > - if (n_stats && !data)
> > - return -ENOMEM;
> > +
> > + if (n_stats) {
> > + data = vzalloc(array_size(n_stats, sizeof(u64)));
> > + if (!data)
> > + return -ENOMEM;
> > + } else {
> > + data = NULL;
> > + }
> >
> > if (dev->phydev && !ops->get_ethtool_phy_stats) {
> > ret = phy_ethtool_get_stats(dev->phydev, &stats, data);
> > if (ret < 0)
> > - return ret;
> > + goto out;
> > } else {
> > ops->get_ethtool_phy_stats(dev, &stats, data);
> > }
> > --
> > 2.16.2
> >
