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-rw-r--r--net/core/ethtool.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 9255bbd..ab5fa63 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -1320,10 +1320,19 @@ static int ethtool_get_dump_data(struct net_device *dev,
if (ret)
return ret;
- len = (tmp.len > dump.len) ? dump.len : tmp.len;
+ len = min(tmp.len, dump.len);
if (!len)
return -EFAULT;
+ /* Don't ever let the driver think there's more space available
+ * than it requested with .get_dump_flag().
+ */
+ dump.len = len;
+
+ /* Always allocate enough space to hold the whole thing so that the
+ * driver does not need to check the length and bother with partial
+ * dumping.
+ */
data = vzalloc(tmp.len);
if (!data)
return -ENOMEM;
@@ -1331,6 +1340,16 @@ static int ethtool_get_dump_data(struct net_device *dev,
if (ret)
goto out;
+ /* There are two sane possibilities:
+ * 1. The driver's .get_dump_data() does not touch dump.len.
+ * 2. Or it may set dump.len to how much it really writes, which
+ * should be tmp.len (or len if it can do a partial dump).
+ * In any case respond to userspace with the actual length of data
+ * it's receiving.
+ */
+ WARN_ON(dump.len != len && dump.len != tmp.len);
+ dump.len = len;
+
if (copy_to_user(useraddr, &dump, sizeof(dump))) {
ret = -EFAULT;
goto out;
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