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    Subject[PATCH] fs/ubifs/orphan.c: remove invalid reference to list iterator variable
    Date
    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 in two
    places.

    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 | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/fs/ubifs/orphan.c b/fs/ubifs/orphan.c
    index b02734d..cebf17e 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;


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