From 8ed95ff262aa8ed37df94b59b84eee93a0b9e133 Mon Sep 17 00:00:00 2001 From: Li RongQing Date: Fri, 29 Mar 2019 09:18:02 +0800 Subject: [PATCH] net: ethtool: not call vzalloc for zero sized memory request [ 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 Reviewed-by: Wang Li Reviewed-by: Michal Kubecek Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/ethtool.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/net/core/ethtool.c b/net/core/ethtool.c index b6bca625b0d2..9a53c66deb64 100644 --- a/net/core/ethtool.c +++ b/net/core/ethtool.c @@ -1287,17 +1287,22 @@ static int ethtool_get_strings(struct net_device *dev, void __user *useraddr) 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; @@ -1385,17 +1390,21 @@ static int ethtool_get_stats(struct net_device *dev, void __user *useraddr) 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;