[PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[Zheng Wang]

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@163.com>
---
 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;
 
@@ -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);
-- 
2.25.1

Re: [PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[Coly Li]

> 2023年2月2日 23:15，Zheng Wang <zyytlz.wz@163.com> 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@163.com>
> ---
> 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.

Thanks.

Coly Li

Re: [PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[Zheng Hacker]

Coly Li <colyli@suse.de> 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@163.com> 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@163.com>
> > ---
> > 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

Re: [PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[Eric Wheeler]

On Thu, 2 Feb 2023, Zheng Wang wrote:

> 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@163.com>

Be sure to add `Cc: stable@vger.kernel.org`

-Eric

> ---
>  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;
>  
> @@ -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);
> -- 
> 2.25.1
> 
> 

Re: [PATCH] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

[Zheng Hacker]

Eric Wheeler <bcache@lists.ewheeler.net> 于2023年2月3日周五 04:37写道：
>
> On Thu, 2 Feb 2023, Zheng Wang wrote:
>
> > 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@163.com>
>
> Be sure to add `Cc: stable@vger.kernel.org`
>
> -Eric
>

Thanks for your kind reminding. Will do in the next patch.

Best regards,
Zheng Wang