linux-kernel - [ 025/153] UBIFS: fix double free of ubifs

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Message-Id: <20130304033710.028488258@decadent.org.uk>
Date:	Mon, 04 Mar 2013 03:37:32 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, Adam Thomas <adamthomas1111@...il.com>,
	Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
Subject: [ 025/153] UBIFS: fix double free of ubifs_orphan objects

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Adam Thomas <adamthomas1111@...il.com>

commit 8afd500cb52a5d00bab4525dd5a560d199f979b9 upstream.

The last orphan in the dnext list has its dnext set to NULL. Because
of that, ubifs_delete_orphan assumes that it is not on the dnext list
and frees it immediately instead ignoring it as a second delete. The
orphan is later freed again by erase_deleted.

This change adds an explicit flag to ubifs_orphan indicating whether
it is pending delete.

Signed-off-by: Adam Thomas <adamthomas1111@...il.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/ubifs/orphan.c |    5 ++++-
 fs/ubifs/ubifs.h  |    2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

--- a/fs/ubifs/orphan.c
+++ b/fs/ubifs/orphan.c
@@ -130,13 +130,14 @@ void ubifs_delete_orphan(struct ubifs_in
 		else if (inum > o->inum)
 			p = p->rb_right;
 		else {
-			if (o->dnext) {
+			if (o->del) {
 				spin_unlock(&c->orphan_lock);
 				dbg_gen("deleted twice ino %lu",
 					(unsigned long)inum);
 				return;
 			}
 			if (o->cnext) {
+				o->del = 1;
 				o->dnext = c->orph_dnext;
 				c->orph_dnext = o;
 				spin_unlock(&c->orphan_lock);
@@ -447,6 +448,7 @@ static void erase_deleted(struct ubifs_i
 		orphan = dnext;
 		dnext = orphan->dnext;
 		ubifs_assert(!orphan->new);
+		ubifs_assert(orphan->del);
 		rb_erase(&orphan->rb, &c->orph_tree);
 		list_del(&orphan->list);
 		c->tot_orphans -= 1;
@@ -536,6 +538,7 @@ static int insert_dead_orphan(struct ubi
 	rb_link_node(&orphan->rb, parent, p);
 	rb_insert_color(&orphan->rb, &c->orph_tree);
 	list_add_tail(&orphan->list, &c->orph_list);
+	orphan->del = 1;
 	orphan->dnext = c->orph_dnext;
 	c->orph_dnext = orphan;
 	dbg_mnt("ino %lu, new %d, tot %d", (unsigned long)inum,
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -908,6 +908,7 @@ struct ubifs_budget_req {
  * @dnext: next orphan to delete
  * @inum: inode number
  * @new: %1 => added since the last commit, otherwise %0
+ * @del: %1 => delete pending, otherwise %0
  */
 struct ubifs_orphan {
 	struct rb_node rb;
@@ -917,6 +918,7 @@ struct ubifs_orphan {
 	struct ubifs_orphan *dnext;
 	ino_t inum;
 	int new;
+	unsigned del:1;
 };
 
 /**


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