linux-kernel - Re: [PATCH v2 6/9] ext4: add positive int attr pointer to avoid sysfs variables overflow

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Message-ID: <20240314103334.pvfgvw4dw7a27unb@quack3>
Date: Thu, 14 Mar 2024 11:33:34 +0100
From: Jan Kara <jack@...e.cz>
To: Baokun Li <libaokun1@...wei.com>
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca,
	jack@...e.cz, ritesh.list@...il.com, ojaswin@...ux.ibm.com,
	adobriyan@...il.com, linux-kernel@...r.kernel.org,
	yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH v2 6/9] ext4: add positive int attr pointer to avoid
 sysfs variables overflow

On Tue 27-02-24 17:11:45, Baokun Li wrote:
> The following variables controlled by the sysfs interface are of type
> int and are normally used in the range [0, INT_MAX], but are declared as
> attr_pointer_ui, and thus may be set to values that exceed INT_MAX and
> result in overflows to get negative values.
> 
>   err_ratelimit_burst
>   msg_ratelimit_burst
>   warning_ratelimit_burst
>   err_ratelimit_interval_ms
>   msg_ratelimit_interval_ms
>   warning_ratelimit_interval_ms
> 
> Therefore, we add attr_pointer_pi (aka positive int attr pointer) with a
> value range of 0-INT_MAX to avoid overflow.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/sysfs.c | 25 +++++++++++++++++++------
>  1 file changed, 19 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
> index 8e0473169458..ddb54608ca2e 100644
> --- a/fs/ext4/sysfs.c
> +++ b/fs/ext4/sysfs.c
> @@ -32,6 +32,7 @@ typedef enum {
>  	attr_clusters_in_group,
>  	attr_mb_order,
>  	attr_feature,
> +	attr_pointer_pi,
>  	attr_pointer_ui,
>  	attr_pointer_ul,
>  	attr_pointer_u64,
> @@ -180,6 +181,9 @@ static struct ext4_attr ext4_attr_##_name = {			\
>  #define EXT4_RO_ATTR_ES_STRING(_name,_elname,_size)			\
>  	EXT4_ATTR_STRING(_name, 0444, _size, ext4_super_block, _elname)
>  
> +#define EXT4_RW_ATTR_SBI_PI(_name,_elname)      \
> +	EXT4_ATTR_OFFSET(_name, 0644, pointer_pi, ext4_sb_info, _elname)
> +
>  #define EXT4_RW_ATTR_SBI_UI(_name,_elname)	\
>  	EXT4_ATTR_OFFSET(_name, 0644, pointer_ui, ext4_sb_info, _elname)
>  
> @@ -222,12 +226,12 @@ EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
>  EXT4_RW_ATTR_SBI_UI(mb_max_linear_groups, s_mb_max_linear_groups);
>  EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
>  EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
> -EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
> -EXT4_RW_ATTR_SBI_UI(err_ratelimit_burst, s_err_ratelimit_state.burst);
> -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
> -EXT4_RW_ATTR_SBI_UI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
> -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
> -EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
> +EXT4_RW_ATTR_SBI_PI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
> +EXT4_RW_ATTR_SBI_PI(err_ratelimit_burst, s_err_ratelimit_state.burst);
> +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_interval_ms, s_warning_ratelimit_state.interval);
> +EXT4_RW_ATTR_SBI_PI(warning_ratelimit_burst, s_warning_ratelimit_state.burst);
> +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_interval_ms, s_msg_ratelimit_state.interval);
> +EXT4_RW_ATTR_SBI_PI(msg_ratelimit_burst, s_msg_ratelimit_state.burst);
>  #ifdef CONFIG_EXT4_DEBUG
>  EXT4_RW_ATTR_SBI_UL(simulate_fail, s_simulate_fail);
>  #endif
> @@ -382,6 +386,7 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a,
>  	case attr_inode_readahead:
>  	case attr_clusters_in_group:
>  	case attr_mb_order:
> +	case attr_pointer_pi:
>  	case attr_pointer_ui:
>  		if (a->attr_ptr == ptr_ext4_super_block_offset)
>  			return sysfs_emit(buf, "%u\n", le32_to_cpup(ptr));
> @@ -452,6 +457,14 @@ static ssize_t ext4_generic_attr_store(struct ext4_attr *a,
>  		return 0;
>  
>  	switch (a->attr_id) {
> +	case attr_pointer_pi:
> +		ret = kstrtouint(skip_spaces(buf), 0, &t);
> +		if (ret)
> +			return ret;
> +		if ((int)t < 0)
> +			return -EINVAL;
> +		*((unsigned int *) ptr) = t;
> +		return len;
>  	case attr_pointer_ui:
>  		ret = kstrtouint(skip_spaces(buf), 0, &t);
>  		if (ret)
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR