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 | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)
--- a/net/core/ethtool.c +++ b/net/core/ethtool.c @@ -1257,17 +1257,22 @@ static int ethtool_get_strings(struct ne
gstrings.len = ret;
- data = kcalloc(gstrings.len, ETH_GSTRING_LEN, GFP_USER); - if (!data) - return -ENOMEM; + if (gstrings.len) { + data = kcalloc(gstrings.len, ETH_GSTRING_LEN, GFP_USER); + 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))) goto out; useraddr += sizeof(gstrings); - if (copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN)) + if (gstrings.len && + copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN)) goto out; ret = 0;
@@ -1355,17 +1360,21 @@ static int ethtool_get_stats(struct net_ return -EFAULT;
stats.n_stats = n_stats; - data = kmalloc(n_stats * sizeof(u64), GFP_USER); - if (!data) - return -ENOMEM; + if (n_stats) { + data = kmalloc(n_stats * sizeof(u64), GFP_USER); + if (!data) + return -ENOMEM;
- ops->get_ethtool_stats(dev, &stats, data); + ops->get_ethtool_stats(dev, &stats, data); + } else { + data = NULL; + }
ret = -EFAULT; if (copy_to_user(useraddr, &stats, sizeof(stats))) goto out; useraddr += sizeof(stats); - if (copy_to_user(useraddr, data, stats.n_stats * sizeof(u64))) + if (n_stats && copy_to_user(useraddr, data, n_stats * sizeof(u64))) goto out; ret = 0;