On Fri, 11 Mar 2022 11:20:35 +0800
Jiasheng Jiang <jiasheng@xxxxxxxxxxx> wrote:
> As the potential failure of the kvmalloc_array(),
> it should be better to check and restore the 'data'
> if fails in order to avoid the dereference of the
> NULL pointer.
>
> Fixes: 6ae746711263 ("hv_netvsc: Add per-cpu ethtool stats for netvsc")
> Signed-off-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx>
> ---
> drivers/net/hyperv/netvsc_drv.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
> index 3646469433b1..018c4a5f6f44 100644
> --- a/drivers/net/hyperv/netvsc_drv.c
> +++ b/drivers/net/hyperv/netvsc_drv.c
> @@ -1587,6 +1587,12 @@ static void netvsc_get_ethtool_stats(struct net_device *dev,
> pcpu_sum = kvmalloc_array(num_possible_cpus(),
> sizeof(struct netvsc_ethtool_pcpu_stats),
> GFP_KERNEL);
> + if (!pcpu_sum) {
> + for (j = 0; j < i; j++)
> + data[j] = 0;
> + return;
> + }
I don't think you understood what my comment was.
The zeroing here is not necessary. Just do:
if (!pcpu_sum)
return;
The data pointer is to buffer allocated here:
static int ethtool_get_stats(struct net_device *dev, void __user *useraddr)
{
...
if (n_stats) {
data = vzalloc(array_size(n_stats, sizeof(u64))); <<<<< is already zeroed.
if (!data)
return -ENOMEM;
ops->get_ethtool_stats(dev, &stats, data);
