Commit c34186ed authored Aug 27, 2010 by Julia Lawall Committed by David S. Miller Aug 27, 2010

net/ipv4: Eliminate kstrdup memory leak

The string clone is only used as a temporary copy of the argument val
within the while loop, and so it should be freed before leaving the
function.  The call to strsep, however, modifies clone, so a pointer to the
front of the string is kept in saved_clone, to make it possible to free it.

The sematic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/

)

// <smpl>
@r exists@
local idexpression x;
expression E;
identifier l;
statement S;
@@

*x= \(kasprintf\|kstrdup\)(...);
...
if (x == NULL) S
... when != kfree(x)
    when != E = x
if (...) {
  <... when != kfree(x)
* goto l;
  ...>
* return ...;
}
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 7e368739

net/ipv4/tcp_cong.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -196,10 +196,10 @@ void tcp_get_allowed_congestion_control(char *buf, size_t maxlen)
		int tcp_set_allowed_congestion_control(char *val)
		{
		struct tcp_congestion_ops *ca;
		char clone, name;
		char saved_clone, clone, *name;
		int ret = 0;

		clone = kstrdup(val, GFP_USER);
		saved_clone = clone = kstrdup(val, GFP_USER);
		if (!clone)
		return -ENOMEM;

		@@ -226,6 +226,7 @@ int tcp_set_allowed_congestion_control(char *val)
		}
		out:
		spin_unlock(&tcp_cong_list_lock);
		kfree(saved_clone);

		return ret;
		}

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