linux-kernel - Re: [PATCH -next] sysctl: returns -EINVAL when a negative value is passed to proc_doulongvec

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Date:   Tue, 14 Dec 2021 16:00:53 +0800
From:   "libaokun (A)" <libaokun1@...wei.com>
To:     <mcgrof@...nel.org>, <keescook@...omium.org>, <yzaikin@...gle.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <yukuai3@...wei.com>, Hulk Robot <hulkci@...wei.com>,
        Baokun Li <libaokun1@...wei.com>
Subject: Re: [PATCH -next] sysctl: returns -EINVAL when a negative value is
 passed to proc_doulongvec_minmax

在 2021/12/9 16:56, Baokun Li 写道:
> When we pass a negative value to the proc_doulongvec_minmax() function,
> the function returns 0, but the corresponding interface value does not
> change.
>
> we can easily reproduce this problem with the following commands:
>      `cd /proc/sys/fs/epoll`
>      `echo -1 > max_user_watches; echo $?; cat max_user_watches`
>
> This function requires a non-negative number to be passed in, so when
> a negative number is passed in, -EINVAL is returned.
>
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> ---
>   kernel/sysctl.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 7f07b058b180..537d2f75faa0 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1149,10 +1149,9 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table,
>   					     sizeof(proc_wspace_sep), NULL);
>   			if (err)
>   				break;
> -			if (neg)
> -				continue;
> +
>   			val = convmul * val / convdiv;
> -			if ((min && val < *min) || (max && val > *max)) {
> +			if (neg || (min && val < *min) || (max && val > *max)) {
>   				err = -EINVAL;
>   				break;
>   			}

ping