From: Li RongQing lirongqing@baidu.com
[ Upstream commit 3d8830266ffc28c16032b859e38a0252e014b631 ]
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 functions which maybe derefence the NULL 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 lirongqing@baidu.com Reviewed-by: Wang Li wangli39@baidu.com Reviewed-by: Michal Kubecek mkubecek@suse.cz Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/ethtool.c | 43 +++++++++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 16 deletions(-)
--- a/net/core/ethtool.c +++ b/net/core/ethtool.c @@ -1815,11 +1815,15 @@ static int ethtool_get_strings(struct ne WARN_ON_ONCE(!ret);
gstrings.len = ret; - data = vzalloc(gstrings.len * ETH_GSTRING_LEN); - if (gstrings.len && !data) - return -ENOMEM; + if (gstrings.len) { + data = vzalloc(gstrings.len * ETH_GSTRING_LEN); + if (!data) + return -ENOMEM;
- __ethtool_get_strings(dev, gstrings.string_set, data); + __ethtool_get_strings(dev, gstrings.string_set, data); + } else { + data = NULL; + }
ret = -EFAULT; if (copy_to_user(useraddr, &gstrings, sizeof(gstrings))) @@ -1915,11 +1919,14 @@ static int ethtool_get_stats(struct net_ return -EFAULT;
stats.n_stats = n_stats; - data = vzalloc(n_stats * sizeof(u64)); - if (n_stats && !data) - return -ENOMEM; - - ops->get_ethtool_stats(dev, &stats, data); + if (n_stats) { + data = vzalloc(n_stats * sizeof(u64)); + if (!data) + return -ENOMEM; + ops->get_ethtool_stats(dev, &stats, data); + } else { + data = NULL; + }
ret = -EFAULT; if (copy_to_user(useraddr, &stats, sizeof(stats))) @@ -1955,13 +1962,17 @@ static int ethtool_get_phy_stats(struct return -EFAULT;
stats.n_stats = n_stats; - data = vzalloc(n_stats * sizeof(u64)); - if (n_stats && !data) - return -ENOMEM; - - mutex_lock(&phydev->lock); - phydev->drv->get_stats(phydev, &stats, data); - mutex_unlock(&phydev->lock); + if (n_stats) { + data = vzalloc(n_stats * sizeof(u64)); + if (!data) + return -ENOMEM; + + mutex_lock(&phydev->lock); + phydev->drv->get_stats(phydev, &stats, data); + mutex_unlock(&phydev->lock); + } else { + data = NULL; + }
ret = -EFAULT; if (copy_to_user(useraddr, &stats, sizeof(stats)))