linux-kernel - Re: [patch] kexec: return -EFAULT on copy_to

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Date:	Thu, 29 Jul 2010 15:58:15 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Dan Carpenter <error27@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Simon Kagstrom <simon.kagstrom@...insight.net>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch] kexec: return -EFAULT on copy_to_user() failures

On Thu, Jul 29, 2010 at 09:36:10AM +0200, Dan Carpenter wrote:
>copy_to/from_user() returns the number of bytes remaining to be copied.
>It never returns a negative value.  The correct return code is -EFAULT
>and not -EIO.
>
>All the callers check for non-zero returns so that's Ok, but the return
>code is passed to the user so we should fix this.
>
>Signed-off-by: Dan Carpenter <error27@...il.com>


Acked-by: WANG Cong <xiyou.wangcong@...il.com>

>
>diff --git a/kernel/kexec.c b/kernel/kexec.c
>index 474a847..ab2258b 100644
>--- a/kernel/kexec.c
>+++ b/kernel/kexec.c
>@@ -151,8 +151,10 @@ static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
> 	image->nr_segments = nr_segments;
> 	segment_bytes = nr_segments * sizeof(*segments);
> 	result = copy_from_user(image->segment, segments, segment_bytes);
>-	if (result)
>+	if (result) {
>+		result = -EFAULT;
> 		goto out;
>+	}
> 
> 	/*
> 	 * Verify we have good destination addresses.  The caller is
>@@ -827,7 +829,7 @@ static int kimage_load_normal_segment(struct kimage *image,
> 		result = copy_from_user(ptr, buf, uchunk);
> 		kunmap(page);
> 		if (result) {
>-			result = (result < 0) ? result : -EIO;
>+			result = -EFAULT;
> 			goto out;
> 		}
> 		ubytes -= uchunk;
>@@ -882,7 +884,7 @@ static int kimage_load_crash_segment(struct kimage *image,
> 		kexec_flush_icache_page(page);
> 		kunmap(page);
> 		if (result) {
>-			result = (result < 0) ? result : -EIO;
>+			result = -EFAULT;
> 			goto out;
> 		}
> 		ubytes -= uchunk;
>--
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