Re: [PATCH v3 01/10] liveupdate: Pass user argument to file preserve and retrieve

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] liveupdate: karg __free(kfree) declared as NULL at top of luo_copy_user_arg()
--

commit c4f18d427b088994ba26ccc665552744e8d63e5a
Author: Pasha Tatashin <pasha.tatashin@soleen.com>

liveupdate: Pass user argument to file preserve and retrieve

This commit extends LIVEUPDATE_SESSION_PRESERVE_FD and
LIVEUPDATE_SESSION_RETRIEVE_FD with an optional user-space argument pointer,
allowing file handlers to specify and receive handler-specific argument
structures during file preservation and retrieval.

> diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
> index a39992da504fb..eeeb3b5ff2faa 100644
> --- a/kernel/liveupdate/luo_file.c
> +++ b/kernel/liveupdate/luo_file.c
[ ... ]
> @@ -202,11 +203,45 @@ static bool luo_token_is_used(struct luo_file_set *file_set, u64 token)
>  	return false;
>  }
>  
> +static int luo_copy_user_arg(u64 user_arg, const void **argp,
> +			     const struct liveupdate_arg_spec *spec)
> +{
> +	void *karg __free(kfree) = NULL;
> +	void __user *uptr;
> +	u32 user_size;
> +	int err;
> +
> +	if (!user_arg)
> +		return 0;
> +	if (!spec->size)
> +		return -EOPNOTSUPP;
> +
> +	uptr = u64_to_user_ptr(user_arg);
> +	if (get_user(user_size, (u32 __user *)uptr))
> +		return -EFAULT;
> +	if (user_size < spec->min_size)
> +		return -EINVAL;
> +	if (user_size > PAGE_SIZE)
> +		return -E2BIG;
> +
> +	karg = kmalloc(spec->size, GFP_KERNEL);
> +	if (!karg)
> +		return -ENOMEM;

[Severity: Low]
This isn't a bug, but in luo_copy_user_arg(), karg is declared with
__free(kfree) = NULL at the top of the function and assigned later after the
early validation checks.

Per the Cleanup API conventions in include/linux/cleanup.h, could karg be
defined and initialized in a single statement at the allocation site instead:

	void *karg __free(kfree) = kmalloc(spec->size, GFP_KERNEL);
	if (!karg)
		return -ENOMEM;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261103010216.3447716-1-dmatlack@google.com?part=1