Re: [PATCH v12 5/9] livepatch: Implement provides and obsoletes for scoped atomic replace

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] livepatch: memory leak of dynamically allocated patch structures on klp_enable_patch failure
--

commit 160ccf1ed36fde593c80db0147adb4d9a0aa689f
Author: Yafang Shao <laoar.shao@gmail.com>

livepatch: Implement provides and obsoletes for scoped atomic replace

This commit replaces the boolean replace flag in klp_patch with provides
and obsoletes fields. It introduces a new flexible model to allow multiple
independent livepatch sets to coexist safely on the same system.

> diff --git a/scripts/livepatch/init.c b/scripts/livepatch/init.c
> index f14d8c8fb35fa..1eb124191cf22 100644
> --- a/scripts/livepatch/init.c
> +++ b/scripts/livepatch/init.c

[ ... ]

> @@ -72,15 +75,19 @@ static int __init livepatch_mod_init(void)
>  
>  	/* TODO patch->states */
>  
> -#ifdef KLP_NO_REPLACE
> -	patch->replace = false;
> -#else
> -	patch->replace = true;
> +#ifdef KLP_PROVIDES
> +	patch->provides = KLP_PROVIDES;
> +#endif
> +#ifdef KLP_OBSOLETES
> +	patch->obsoletes = klp_obsoletes;
> +	patch->nr_obsoletes = ARRAY_SIZE(klp_obsoletes);
>  #endif
>  
>  	return klp_enable_patch(patch);

[Severity: Medium]
If klp_enable_patch() fails (e.g., due to patch incompatibility or early
-ENODEV) and returns an error code, does this direct return bypass the 
err_free_objs cleanup path below?

The primary structures (patch, objs, and funcs) are allocated with kzalloc()
earlier in livepatch_mod_init(). Because the core livepatch error path inside
klp_enable_patch() treats these structures as statically provided by the module,
it will not kfree() them upon failure. 

Does this code permanently leak the patch, objs, and funcs structures? Would it
be better to save the return status and goto err_free_objs on failure?

>  
>  err_free_objs:
> +	for (int i = 0; i < nr_objs; i++)
> +		kfree(objs[i].funcs);
>  	kfree(objs);
>  err_free_patch:
>  	kfree(patch);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261016053708.47089-1-laoar.shao@gmail.com?part=5