2023-02-18 07:24:25

by Zheng Wang

Subject: [RESEND PATCH v3] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

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")
Cc: [email protected]
Signed-off-by: Zheng Wang <[email protected]>
---
v3:
- Add Cc: [email protected] suggested by Eric
v2:
- split patch v1 into two patches to make it clearer suggested by Coly Li
---
drivers/md/bcache/btree.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 147c493a989a..cae25e74b9e0 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;

--
2.25.1

2023-02-18 15:22:46

by Coly Li

Subject: Re: [RESEND PATCH v3] bcache: Fix __bch_btree_node_alloc to make the failure behavior consistent

On Sat, Feb 18, 2023 at 03:23:35PM +0800, 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")
> Cc: [email protected]
> Signed-off-by: Zheng Wang <[email protected]>

Thanks, I will add this series to my for-next testing queue.

Coly Li

> ---
> v3:
> - Add Cc: [email protected] suggested by Eric
> v2:
> - split patch v1 into two patches to make it clearer suggested by Coly Li
> ---
> drivers/md/bcache/btree.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index 147c493a989a..cae25e74b9e0 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;
>
> --
> 2.25.1
>