maple_tree: Fix mas_empty_area_rev() search exhaustion at root node

Commit Message

Liam R. Howlett July 12, 2022, 1:50 a.m. UTC

When the possibilities of finding a gap are exhausted at the root node,
the error code was not returned which results in returning a range that
is currently occupied.  Add the necessary check for the error code and
return to the caller.

Reported-by: Alexander Gordeev <[e-mail]>
Fixes: d0aac5e48048 (Maple Tree: add new data structure)
Signed-off-by: Liam R. Howlett <[e-mail]>
---
 lib/maple_tree.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Alexander Gordeev July 12, 2022, 11:51 a.m. UTC | #1

On Tue, Jul 12, 2022 at 01:50:36AM +0000, Liam Howlett wrote:
> When the possibilities of finding a gap are exhausted at the root node,
> the error code was not returned which results in returning a range that
> is currently occupied.  Add the necessary check for the error code and
> return to the caller.
> 
> Reported-by: Alexander Gordeev <[e-mail]>
> Fixes: d0aac5e48048 (Maple Tree: add new data structure)
> Signed-off-by: Liam R. Howlett <[e-mail]>
> ---
>  lib/maple_tree.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/lib/maple_tree.c b/lib/maple_tree.c
> index 9dc4ffff18d0..14e9ab14c1da 100644
> --- a/lib/maple_tree.c
> +++ b/lib/maple_tree.c
> @@ -5287,6 +5287,9 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
>  		}
>  	}
>  
> +	if (mas_is_err(mas))
> +		return xa_err(mas->node);
> +
>  	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
>  		return -EBUSY;

Tested-by: Alexander Gordeev <[e-mail]>

Thanks!

Patch

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 9dc4ffff18d0..14e9ab14c1da 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5287,6 +5287,9 @@  int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
 		}
 	}
 
+	if (mas_is_err(mas))
+		return xa_err(mas->node);
+
 	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
 		return -EBUSY;