linux-kernel - Re: [PATCH] proc: use vmalloc for our kernel buffer

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Message-ID: <20200813145941.GJ17456@casper.infradead.org>
Date:   Thu, 13 Aug 2020 15:59:41 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Josef Bacik <josef@...icpanda.com>
Cc:     hch@....de, viro@...iv.linux.org.uk, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH] proc: use vmalloc for our kernel buffer

On Thu, Aug 13, 2020 at 10:53:05AM -0400, Josef Bacik wrote:
> +/**
> + * vmemdup_user - duplicate memory region from user space and NUL-terminate

vmemdup_user_nul()

> +void *vmemdup_user_nul(const void __user *src, size_t len)
> +{
> +	void *p;
> +
> +	p = kvmalloc(len, GFP_USER);

len+1, shirley?

> +	if (!p)
> +		return ERR_PTR(-ENOMEM);
> +
> +	if (copy_from_user(p, src, len)) {
> +		kvfree(p);
> +		return ERR_PTR(-EFAULT);
> +	}

I think you forgot

        p[len] = '\0';

> +	return p;
> +}
> +EXPORT_SYMBOL(vmemdup_user_nul);
> +
>  /**
>   * strndup_user - duplicate an existing string from user space
>   * @s: The string to duplicate
> -- 
> 2.24.1
>