[PATCH 5.0 012/117] net: ethtool: not call vzalloc for zero sized memory request

Greg Kroah-Hartman
2019-04-15T19:19:47Z

[ 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: Sasha Levin <sashal@kernel.org>
---
net/core/ethtool.c | 46 ++++++++++++++++++++++++++++++----------------
1 file changed, 30 insertions(+), 16 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 158264f7cfaf..3a7f19a61768 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1794,11 +1794,16 @@ static int ethtool_get_strings(struct net_device *dev, void __user *useraddr)
WARN_ON_ONCE(!ret);

gstrings.len = ret;
- data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN));
- if (gstrings.len && !data)
- return -ENOMEM;

- __ethtool_get_strings(dev, gstrings.string_set, data);
+ if (gstrings.len) {
+ data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN));
+ if (!data)
+ return -ENOMEM;
+
+ __ethtool_get_strings(dev, gstrings.string_set, data);
+ } else {
+ data = NULL;
+ }

ret = -EFAULT;
if (copy_to_user(useraddr, &gstrings, sizeof(gstrings)))
@@ -1894,11 +1899,15 @@ 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;

- ops->get_ethtool_stats(dev, &stats, data);
+ if (n_stats) {
+ data = vzalloc(array_size(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)))
@@ -1938,16 +1947,21 @@ 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 (dev->phydev && !ops->get_ethtool_phy_stats) {
- ret = phy_ethtool_get_stats(dev->phydev, &stats, data);
- if (ret < 0)
- return ret;
+ if (n_stats) {
+ data = vzalloc(array_size(n_stats, sizeof(u64)));
+ if (!data)
+ return -ENOMEM;
+
+ if (dev->phydev && !ops->get_ethtool_phy_stats) {
+ ret = phy_ethtool_get_stats(dev->phydev, &stats, data);
+ if (ret < 0)
+ goto out;
+ } else {
+ ops->get_ethtool_phy_stats(dev, &stats, data);
+ }
} else {
- ops->get_ethtool_phy_stats(dev, &stats, data);
+ data = NULL;
}

ret = -EFAULT;
--
2.19.1