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Date:   Thu, 30 Dec 2021 01:15:10 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Stefan Roesch <shr@fb.com>
Cc:     io-uring@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        kernel-team@fb.com, torvalds@linux-foundation.org,
        christian.brauner@ubuntu.com
Subject: Re: [PATCH v10 2/5] fs: split off setxattr_copy and do_setxattr
 function from setxattr
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References: <20211229203002.4110839-1-shr@fb.com>
 <20211229203002.4110839-3-shr@fb.com>
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On Wed, Dec 29, 2021 at 12:29:59PM -0800, Stefan Roesch wrote:
> +	if (ctx->size) {
> +		if (ctx->size > XATTR_SIZE_MAX)
>  			return -E2BIG;
> -		kvalue = kvmalloc(size, GFP_KERNEL);
> -		if (!kvalue)
> +
> +		ctx->kvalue = kvmalloc(ctx->size, GFP_KERNEL);
> +		if (!ctx->kvalue)
>  			return -ENOMEM;
> -		if (copy_from_user(kvalue, value, size)) {
> -			error = -EFAULT;
> -			goto out;
> +
> +		if (copy_from_user(ctx->kvalue, ctx->value, ctx->size)) {
> +			kvfree(ctx->kvalue);
> +			return -EFAULT;

BTW, what's wrong with using vmemdup_user() here?