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Subject[PATCH 4.14 35/69] net: ethtool: not call vzalloc for zero sized memory request
Date
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)))

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