From 7074e5eb233343e4bad8c0a3f9e73167cf85a159 Mon Sep 17 00:00:00 2001 From: Julia Lawall Date: Mon, 9 Jul 2012 09:27:14 +0200 Subject: [PATCH] UBIFS: remove invalid reference to list iterator variable 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 in two places. A simplified version of the semantic match that finds this problem is as follows: (http://coccinelle.lip6.fr/) // @@ 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 ) // Artem: fortunately, this did not cause any issues because we iterate the orphan list using the elements count, so we never dereferenced the corrupted pointer. This is why I do not send this patch to -stable. But otherwise - well spotted! Signed-off-by: Julia Lawall Signed-off-by: Artem Bityutskiy --- fs/ubifs/orphan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c index b02734db187c..cebf17ea0458 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); @@ -382,7 +382,7 @@ static int consolidate(struct ubifs_info *c) last = &orphan->cnext; cnt += 1; } - *last = orphan->cnext; + *last = NULL; ubifs_assert(cnt == c->tot_orphans - c->new_orphans); c->cmt_orphans = cnt; c->ohead_lnum = c->orph_first;