Apr 02 2010

powerpc/pseries/dlpar: Eliminate use after free 

Author: Julia Lawall <julia@diku.dk>

dlpar_free_cc_nodes frees its argument, so dlpar_online_cpu should not be
called on the same value.  Skip over the call to dlpar_online_cpu by
jumping directly to out.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// 
@@
expression E,E2;
@@

dlpar_free_cc_nodes(E)
...
(
  E = E2
|
* E
)
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Benjamin Herrenschmidt 

---
 arch/powerpc/platforms/pseries/dlpar.c | 1 +
 1 file changed, 1 insertion(+)
 
diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index e1682bc..1540a41 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -433,6 +433,7 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 	if (rc) {
 		dlpar_release_drc(drc_index);
 		dlpar_free_cc_nodes(dn);
+		goto out;
 	}
 
 	rc = dlpar_online_cpu(dn);

qlambert