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Commit 63f74ca2 authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
Browse files

mempolicy: fix refcount leak in mpol_set_shared_policy() 



When shared_policy_replace() fails to allocate new->policy is not freed
correctly by mpol_set_shared_policy().  The problem is that shared
mempolicy code directly call kmem_cache_free() in multiple places where
it is easy to make a mistake.

This patch creates an sp_free wrapper function and uses it. The bug was
introduced pre-git age (IOW, before 2.6.12-rc2).

[mgorman@suse.de: Editted changelog]
Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarMel Gorman <mgorman@suse.de>
Reviewed-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Josh Boyer <jwboyer@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b22d127a

mm/mempolicy.c

+9 −6
Original line number Diff line number Diff line
@@ -2157,12 +2157,17 @@ mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx) 
	return pol;

}



static void sp_free(struct sp_node *n)

{

	mpol_put(n->policy);

	kmem_cache_free(sn_cache, n);

}



static void sp_delete(struct shared_policy *sp, struct sp_node *n)

{

	pr_debug("deleting %lx-l%lx\n", n->start, n->end);

	rb_erase(&n->nd, &sp->root);

	mpol_put(n->policy);

	kmem_cache_free(sn_cache, n);

	sp_free(n);

}



static struct sp_node *sp_alloc(unsigned long start, unsigned long end,
@@ -2301,7 +2306,7 @@ int mpol_set_shared_policy(struct shared_policy *info, 
	}

	err = shared_policy_replace(info, vma->vm_pgoff, vma->vm_pgoff+sz, new);

	if (err && new)

		kmem_cache_free(sn_cache, new);

		sp_free(new);

	return err;

}
@@ -2318,9 +2323,7 @@ void mpol_free_shared_policy(struct shared_policy *p) 
	while (next) {

		n = rb_entry(next, struct sp_node, nd);

		next = rb_next(&n->nd);

		rb_erase(&n->nd, &p->root);

		mpol_put(n->policy);

		kmem_cache_free(sn_cache, n);

		sp_delete(p, n);

	}

	mutex_unlock(&p->mutex);

}