[PATCH] Null pointer dereference at free_vm_area()

[glommer@br.ibm.com (Glauber de Oliveira Costa)]

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Hi folks,

The free_vm_area() function may crash if it gets a NULL pointer as a
parameter. I do think that the right behaviour should be returning in
this case. This is, for example, the same behaviour of kfree(), and as
alloc_vm_area() may also return NULL, it may lead to a more elegant 
alloc/free sequence in case of a fail.

In case you agree with that, a patch follows.

Signed-off-by: Glauber de Oliveira Costa <glommer@br.ibm.com>

-- 
glommer

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diff -r 829517be689f linux-2.6-xen-sparse/drivers/xen/util.c
--- a/linux-2.6-xen-sparse/drivers/xen/util.c	Fri Dec 23 15:42:46 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/util.c	Mon Dec 26 15:47:50 2005
@@ -35,6 +35,8 @@
 void free_vm_area(struct vm_struct *area)
 {
 	struct vm_struct *ret;
+	if (!area)
+		return;
 	ret = remove_vm_area(area->addr);
 	BUG_ON(ret != area);
 	kfree(area);

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