linux-kernel - Re: [PATCH v2] bcachefs: early return for negative values when parsing BCH_OPT

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Message-ID: <khrsd3ey6hiedccufg2xhy734vdxzagg4eym3gotjxaizgrx7x@7bo4fpsj7n7f>
Date: Sun, 6 Apr 2025 13:26:19 -0400
From: Kent Overstreet <kent.overstreet@...ux.dev>
To: Integral <integral@...hlinuxcn.org>
Cc: kent.overstreet@...il.com, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] bcachefs: early return for negative values when
 parsing BCH_OPT_UINT

On Sun, Apr 06, 2025 at 10:53:28PM +0800, Integral wrote:
> Currently, when passing a negative integer as argument, the error
> message is "too big" due to casting to an unsigned integer:
> 
>     > bcachefs format --block_size=-1 bcachefs.img
>     invalid option: block_size: too big (max 65536)
> 
> When negative value in argument detected, return early before
> calling bch2_opt_validate().
> 
> A new error code `BCH_ERR_option_negative` is added.
> 
> Signed-off-by: Integral <integral@...hlinuxcn.org>

Applied

> ---
>  fs/bcachefs/errcode.h |  1 +
>  fs/bcachefs/opts.c    | 12 +++++++++---
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/bcachefs/errcode.h b/fs/bcachefs/errcode.h
> index c4eb0ed9838d..e3c85288fd6d 100644
> --- a/fs/bcachefs/errcode.h
> +++ b/fs/bcachefs/errcode.h
> @@ -213,6 +213,7 @@
>  	x(EINVAL,			inode_unpack_error)			\
>  	x(EINVAL,			varint_decode_error)			\
>  	x(EINVAL,			erasure_coding_found_btree_node)	\
> +	x(EINVAL,			option_negative)			\
>  	x(EOPNOTSUPP,			may_not_use_incompat_feature)		\
>  	x(EROFS,			erofs_trans_commit)			\
>  	x(EROFS,			erofs_no_writes)			\
> diff --git a/fs/bcachefs/opts.c b/fs/bcachefs/opts.c
> index e64777ecf44f..1bf2580ab735 100644
> --- a/fs/bcachefs/opts.c
> +++ b/fs/bcachefs/opts.c
> @@ -360,9 +360,15 @@ int bch2_opt_parse(struct bch_fs *c,
>  			return -EINVAL;
>  		}
>  
> -		ret = opt->flags & OPT_HUMAN_READABLE
> -			? bch2_strtou64_h(val, res)
> -			: kstrtou64(val, 10, res);
> +		if (*val != '-') {
> +			ret = opt->flags & OPT_HUMAN_READABLE
> +			    ? bch2_strtou64_h(val, res)
> +			    : kstrtou64(val, 10, res);
> +		} else {
> +			prt_printf(err, "%s: must be a non-negative number", opt->attr.name);
> +			return -BCH_ERR_option_negative;
> +		}
> +
>  		if (ret < 0) {
>  			if (err)
>  				prt_printf(err, "%s: must be a number",
> -- 
> 2.49.0
>