Re: [PATCH] s390: uv: Fix loop condition in uv_find_secrets

["Christoph Schlameuss" <schlameuss@linux.ibm.com>]

On Tue Aug 11, 2026 at 10:43 AM CEST, Steffen Eiden wrote:
> Nothing modified `start_idx` between the assignment and the comparison,
> so the condition was always false and the do/while ran exactly once
> even when the UV returned UVC_RC_MORE_DATA. Systems with more than
> 85 UV secrets got -ENOENT for any secret past the first page.
>
> Fix this by setting the start index at the beginning of the loop not at
> the end. First test if there are more secrets left by comparing
> start_idx with list->next_secret_idx, and then set the start index to the
> next secret index.
>
> Fixes: 7c9137af2042 ("s390/uv: Retrieve UV secrets support")
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>

> ---
>  arch/s390/kernel/uv.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
> index a284f98d9716..d970b15ef126 100644
> --- a/arch/s390/kernel/uv.c
> +++ b/arch/s390/kernel/uv.c
> @@ -781,11 +781,14 @@ int uv_find_secret(const u8 secret_id[UV_SECRET_ID_LEN],
>  		   struct uv_secret_list *list,
>  		   struct uv_secret_list_item_hdr *secret)
>  {
> -	u16 start_idx = 0;
> +	u16 start_idx;
>  	u16 list_rc;
>  	int ret;
>  
> +	list->next_secret_idx = 0;
> +
>  	do {
> +		start_idx = list->next_secret_idx;
>  		uv_list_secrets(list, start_idx, &list_rc, NULL);
>  		if (list_rc != UVC_RC_EXECUTED && list_rc != UVC_RC_MORE_DATA) {
>  			if (list_rc == UVC_RC_INV_CMD)
> @@ -796,7 +799,6 @@ int uv_find_secret(const u8 secret_id[UV_SECRET_ID_LEN],
>  		ret = find_secret_in_page(secret_id, list, secret);
>  		if (ret == 0)
>  			return ret;
> -		start_idx = list->next_secret_idx;
>  	} while (list_rc == UVC_RC_MORE_DATA && start_idx < list->next_secret_idx);
>  
>  	return -ENOENT;
>
> ---
> base-commit: d58772d8520c7ef247c4b95c9bd76d3a25da9ff5
> change-id: 20260811-uv_secrets_fix-58a63b4a4ec4
>
> Best regards,