Coly Li <colyli@xxxxxxx> 于2023年2月3日周五 00:23写道：
>
>
>
> > 2023年2月2日 23:15，Zheng Wang <zyytlz.wz@xxxxxxx> 写道：
> >
> > In some specific situation, the return value of __bch_btree_node_alloc may
> > be NULL. This may lead to poential NULL pointer dereference in caller
> > function like a calling chaion :
> > btree_split->bch_btree_node_alloc->__bch_btree_node_alloc.
> >
> > Fix it by initialize return value in __bch_btree_node_alloc before return.
> >
> > Fixes: cafe56359144 ("bcache: A block layer cache")
> > Signed-off-by: Zheng Wang <zyytlz.wz@xxxxxxx>
> > ---
> > drivers/md/bcache/btree.c | 10 ++++++----
> > drivers/md/bcache/super.c | 2 +-
> > 2 files changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> > index 147c493a989a..35346c1d7c3c 100644
> > --- a/drivers/md/bcache/btree.c
> > +++ b/drivers/md/bcache/btree.c
> > @@ -1090,10 +1090,12 @@ struct btree *__bch_btree_node_alloc(struct cache_set *c, struct btree_op *op,
> > struct btree *parent)
> > {
> > BKEY_PADDED(key) k;
> > - struct btree *b = ERR_PTR(-EAGAIN);
> > + struct btree *b;
> >
> > mutex_lock(&c->bucket_lock);
> > retry:
> > + /* return ERR_PTR(-EAGAIN) when it fails */
> > + b = ERR_PTR(-EAGAIN);
> > if (__bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, wait))
> > goto err;
> >
>
>
> The above change can be a single patch.
>
> And the rested change can be another cleanup patch.
>
> > @@ -1138,7 +1140,7 @@ static struct btree *btree_node_alloc_replacement(struct btree *b,
> > {
> > struct btree *n = bch_btree_node_alloc(b->c, op, b->level, b->parent);
> >
> > - if (!IS_ERR_OR_NULL(n)) {
> > + if (!IS_ERR(n)) {
> > mutex_lock(&n->write_lock);
> > bch_btree_sort_into(&b->keys, &n->keys, &b->c->sort);
> > bkey_copy_key(&n->key, &b->key);
> > @@ -1352,7 +1354,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
> >
> > for (i = 0; i < nodes; i++) {
> > new_nodes[i] = btree_node_alloc_replacement(r[i].b, NULL);
> > - if (IS_ERR_OR_NULL(new_nodes[i]))
> > + if (IS_ERR(new_nodes[i]))
> > goto out_nocoalesce;
> > }
> >
> > @@ -1669,7 +1671,7 @@ static int bch_btree_gc_root(struct btree *b, struct btree_op *op,
> > if (should_rewrite) {
> > n = btree_node_alloc_replacement(b, NULL);
> >
> > - if (!IS_ERR_OR_NULL(n)) {
> > + if (!IS_ERR(n)) {
> > bch_btree_node_write_sync(n);
> >
> > bch_btree_set_root(n);
> > diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> > index ba3909bb6bea..92de714fe75e 100644
> > --- a/drivers/md/bcache/super.c
> > +++ b/drivers/md/bcache/super.c
> > @@ -2088,7 +2088,7 @@ static int run_cache_set(struct cache_set *c)
> >
> > err = "cannot allocate new btree root";
> > c->root = __bch_btree_node_alloc(c, NULL, 0, true, NULL);
> > - if (IS_ERR_OR_NULL(c->root))
> > + if (IS_ERR(c->root))
> > goto err;
> >
> > mutex_lock(&c->root->write_lock);
>
> And there will be 2 patches as I suggested.
>
Got it. It's a little bit late now. I might make that tomorrow ^_^
Best regards,
Zheng Wang
