Patchwork fs/ubifs/orphan.c: remove invalid reference to list iterator variable

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Submitter Julia Lawall
Date July 8, 2012, 1:19 p.m.
Message ID <1341753582-3943-2-git-send-email-Julia.Lawall@lip6.fr>
Download mbox | patch
Permalink /patch/169645/
State New
Headers show

Comments

Julia Lawall - July 8, 2012, 1:19 p.m.
From: Julia Lawall <Julia.Lawall@lip6.fr>

If list_for_each_entry, etc complete a traversal of the list, the iterator
variable ends up pointing to an address at an offset from the list head,
and not a meaningful structure.  Thus this value should not be used after
the end of the iterator.  Replace a field access from orphan by NULL.

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

// <smpl>
@@
identifier c;
expression E;
iterator name list_for_each_entry;
statement S;
@@

list_for_each_entry(c,...) { ... when != break;
                                 when forall
                                 when strict
}
...
(
c = E
|
*c
)
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>

---
 fs/ubifs/orphan.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
index b02734d..4b7860a 100644
--- a/fs/ubifs/orphan.c
+++ b/fs/ubifs/orphan.c
@@ -176,7 +176,7 @@  int ubifs_orphan_start_commit(struct ubifs_info *c)
 		*last = orphan;
 		last = &orphan->cnext;
 	}
-	*last = orphan->cnext;
+	*last = NULL;
 	c->cmt_orphans = c->new_orphans;
 	c->new_orphans = 0;
 	dbg_cmt("%d orphans to commit", c->cmt_orphans);