Re: [PATCH v6 16/17] lib/bootconfig: fix sign-compare in xbc_node_compose_key_after()

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Sun, 15 Mar 2026 12:20:14 +0000
Josh Law <objecting@objecting.org> wrote:

>   lib/bootconfig.c:322:25: warning: comparison of integer expressions
>   of different signedness: 'int' and 'size_t' [-Wsign-compare]
>   lib/bootconfig.c:325:30: warning: conversion to 'size_t' from 'int'
>   may change the sign of the result [-Wsign-conversion]
> 
> snprintf() returns int but size is size_t, so comparing ret >= size
> and subtracting size -= ret involve mixed-sign operations.  Cast ret
> at the comparison and subtraction sites; ret is known non-negative at
> this point because the ret < 0 early return has already been taken.
> 
> Signed-off-by: Josh Law <objecting@objecting.org>
> ---
>  lib/bootconfig.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/bootconfig.c b/lib/bootconfig.c
> index e318b236e728..68a72dbc38fa 100644
> --- a/lib/bootconfig.c
> +++ b/lib/bootconfig.c
> @@ -319,10 +319,10 @@ int __init xbc_node_compose_key_after(struct xbc_node *root,
>  			       depth ? "." : "");
>  		if (ret < 0)
>  			return ret;
> -		if (ret >= size) {
> +		if (ret >= (int)size) {

nit:

	if ((size_t)ret >= size) {

because sizeof(size_t) > sizeof(int).

Thanks,

>  			size = 0;
>  		} else {
> -			size -= ret;
> +			size -= (size_t)ret;
>  			buf += ret;
>  		}
>  		total += ret;
> -- 
> 2.34.1
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>