linux-kernel - Re: [PATCH] put_user() on struct is not nice

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Date:	Wed, 26 Sep 2007 12:05:46 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Al Viro <viro@....linux.org.uk>
Cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] put_user() on struct is not nice

On Wed, 2007-09-26 at 01:54 +0100, Al Viro wrote:
> use copy_to_user() instead...

Thanks Al, Jes sent me the same fix which I have queued for for 2.6.24:

From: Jes Sorensen <jes@....com>

Use copy_to_user() when copying a struct timespec to the guest -
put_user() cannot handle two long's in one go on a 64bit arch.

Signed-off-by: Jes Sorensen <jes@....com>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 drivers/lguest/hypercalls.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

===================================================================
--- linux-2.6.23-rc4.orig/drivers/lguest/hypercalls.c
+++ linux-2.6.23-rc4/drivers/lguest/hypercalls.c
@@ -243,6 +243,6 @@ void write_timestamp(struct lguest *lg)
 {
 	struct timespec now;
 	ktime_get_real_ts(&now);
-	if (put_user(now, &lg->lguest_data->time))
+	if (copy_to_user(&lg->lguest_data->time, &now, sizeof(struct timespec)))
 		kill_guest(lg, "Writing timestamp");
 }


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