From: Andrea Arcangeli <aarcange@redhat.com>
To: akpm@linux-foundation.org
Cc: hugh@veritas.com, linux-kernel@vger.kernel.org,
Izik Eidus <ieidus@redhat.com>,
nickpiggin@yahoo.com.au, chrisw@redhat.com, linux-mm@kvack.org,
riel@redhat.com
Subject: [PATCH] ksm: fix losing visibility of part of rmap_item->next list
Date: Wed, 3 Jun 2009 16:47:23 +0200 [thread overview]
Message-ID: <20090603144723.GC30426@random.random> (raw)
In-Reply-To: <20090603144552.GB30426@random.random>
From: Andrea Arcangeli <aarcange@redhat.com>
The tree_item->rmap_item is the head of the list and as such it must
not be overwritten except in the case that the element we removed
(rmap_item) was the previous head of the list, in which case it would
also have rmap_item->prev set to null.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
diff --git a/mm/ksm.c b/mm/ksm.c
index 74d921b..6d8dfee 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -397,10 +397,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
free_tree_item(tree_item);
nnodes_stable_tree--;
} else if (!rmap_item->prev) {
+ BUG_ON(tree_item->rmap_item != rmap_item);
tree_item->rmap_item = rmap_item->next;
- } else {
- tree_item->rmap_item = rmap_item->prev;
- }
+ } else
+ BUG_ON(tree_item->rmap_item == rmap_item);
} else {
/*
* We dont rb_erase(&tree_item->node) here, beacuse
WARNING: multiple messages have this Message-ID (diff)
From: Andrea Arcangeli <aarcange@redhat.com>
To: akpm@linux-foundation.org
Cc: hugh@veritas.com, linux-kernel@vger.kernel.org,
Izik Eidus <ieidus@redhat.com>,
nickpiggin@yahoo.com.au, chrisw@redhat.com, linux-mm@kvack.org,
riel@redhat.com
Subject: [PATCH] ksm: fix losing visibility of part of rmap_item->next list
Date: Wed, 3 Jun 2009 16:47:23 +0200 [thread overview]
Message-ID: <20090603144723.GC30426@random.random> (raw)
In-Reply-To: <20090603144552.GB30426@random.random>
From: Andrea Arcangeli <aarcange@redhat.com>
The tree_item->rmap_item is the head of the list and as such it must
not be overwritten except in the case that the element we removed
(rmap_item) was the previous head of the list, in which case it would
also have rmap_item->prev set to null.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
diff --git a/mm/ksm.c b/mm/ksm.c
index 74d921b..6d8dfee 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -397,10 +397,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
free_tree_item(tree_item);
nnodes_stable_tree--;
} else if (!rmap_item->prev) {
+ BUG_ON(tree_item->rmap_item != rmap_item);
tree_item->rmap_item = rmap_item->next;
- } else {
- tree_item->rmap_item = rmap_item->prev;
- }
+ } else
+ BUG_ON(tree_item->rmap_item == rmap_item);
} else {
/*
* We dont rb_erase(&tree_item->node) here, beacuse
--
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next prev parent reply other threads:[~2009-06-03 15:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-03 14:45 [PATCH] ksm: fix rmap_item use after free Andrea Arcangeli
2009-06-03 14:45 ` Andrea Arcangeli
2009-06-03 14:47 ` Andrea Arcangeli [this message]
2009-06-03 14:47 ` [PATCH] ksm: fix losing visibility of part of rmap_item->next list Andrea Arcangeli
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