2021-10-12 08:47:54

by Jiasheng Jiang

Subject: [PATCH] XArray: Fix xa_to_node by adding xa_is_node

Directly using xa_to_node may lead to the compulsory type
conversion of unknown type,which is unsafe.
So it might be better that adding xa_is_node before.

Fixes: 58d6ea3 ("xarray: Add XArray unconditional store operations")
Signed-off-by: Jiasheng Jiang <[email protected]>
---
lib/test_xarray.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 8b1c318..7ad3d51 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -606,8 +606,10 @@ static noinline void check_multi_store(struct xarray *xa)
XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
rcu_read_lock();
- XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
- XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
+ if (xa_is_node(xa_head(xa))) {
+ XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
+ XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
+ }
rcu_read_unlock();

/* Storing adjacent to the value does not alter the value */
--
2.7.4

2021-10-18 20:10:06

by Matthew Wilcox

Subject: Re: [PATCH] XArray: Fix xa_to_node by adding xa_is_node

On Tue, Oct 12, 2021 at 08:42:50AM +0000, Jiasheng Jiang wrote:
> Directly using xa_to_node may lead to the compulsory type
> conversion of unknown type,which is unsafe.
> So it might be better that adding xa_is_node before.

No. This is test code, and it knows what it's doing.
I suppose we could add an XA_BUG_ON(xa, !xa_is_node(xa_head(xa)));
but that seems pointless. This patch is definitely wrong.

> Fixes: 58d6ea3 ("xarray: Add XArray unconditional store operations")
> Signed-off-by: Jiasheng Jiang <[email protected]>
> ---
> lib/test_xarray.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/lib/test_xarray.c b/lib/test_xarray.c
> index 8b1c318..7ad3d51 100644
> --- a/lib/test_xarray.c
> +++ b/lib/test_xarray.c
> @@ -606,8 +606,10 @@ static noinline void check_multi_store(struct xarray *xa)
> XA_BUG_ON(xa, xa_load(xa, 1) != xa_mk_value(0));
> XA_BUG_ON(xa, xa_load(xa, 2) != NULL);
> rcu_read_lock();
> - XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
> - XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
> + if (xa_is_node(xa_head(xa))) {
> + XA_BUG_ON(xa, xa_to_node(xa_head(xa))->count != 2);
> + XA_BUG_ON(xa, xa_to_node(xa_head(xa))->nr_values != 2);
> + }
> rcu_read_unlock();
>
> /* Storing adjacent to the value does not alter the value */
> --
> 2.7.4
>