Hi Masami,

On Thu, 2026-05-21 at 13:49 +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <[email protected]>
> 
> In paths where tracing_map_elt_alloc() failed to allocate objects,
> the map->ops->elt_alloc() call was never successful. In this case,
> map->ops->elt_free() should not be called.
> 
> This bug was found by Sashiko.
> Link: https://sashiko.dev/#/patchset/20260520223101.34710-1-rosenp%40gmail.com
> 
> Fixes: 2734b629525a ("tracing: Add per-element variable support to 
> tracing_map")
> Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
> Cc: [email protected]
> ---
>  kernel/trace/tracing_map.c |   17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
> index bf1a507695b6..0dd7927df22a 100644
> --- a/kernel/trace/tracing_map.c
> +++ b/kernel/trace/tracing_map.c
> @@ -386,13 +386,11 @@ static void tracing_map_elt_init_fields(struct 
> tracing_map_elt *elt)
>       }
>  }
>  
> -static void tracing_map_elt_free(struct tracing_map_elt *elt)
> +static void __tracing_map_elt_free(struct tracing_map_elt *elt)
>  {
>       if (!elt)
>               return;
>  
> -     if (elt->map->ops && elt->map->ops->elt_free)
> -             elt->map->ops->elt_free(elt);
>       kfree(elt->fields);
>       kfree(elt->vars);
>       kfree(elt->var_set);
> @@ -400,6 +398,17 @@ static void tracing_map_elt_free(struct tracing_map_elt 
> *elt)
>       kfree(elt);
>  }
>  
> +static void tracing_map_elt_free(struct tracing_map_elt *elt)
> +{
> +     if (!elt)
> +             return;
> +
> +     /* Only objects initialized with alloc_elt() should be passed to 
> free_elt().*/
> +     if (elt->map->ops && elt->map->ops->elt_free)
> +             elt->map->ops->elt_free(elt);
> +     __tracing_map_elt_free(elt);
> +}
> +
>  static struct tracing_map_elt *tracing_map_elt_alloc(struct tracing_map *map)
>  {
>       struct tracing_map_elt *elt;
> @@ -444,7 +453,7 @@ static struct tracing_map_elt 
> *tracing_map_elt_alloc(struct tracing_map *map)
>       }
>       return elt;
>   free:
> -     tracing_map_elt_free(elt);
> +     __tracing_map_elt_free(elt);
>  
>       return ERR_PTR(err);
>  }
> 
> 

Looks good to me. Thanks for fixing it!

Reviewed-by: Tom Zanussi <[email protected]>


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