linux-kernel - [-mm patch] make csum_and_copy_from_user arch independent (was Re: 2.6.21-mm2)

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Date:	Fri, 11 May 2007 10:27:38 +0200
From:	Frederik Deweerdt <deweerdt@...e.fr>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, jorge@...er.satlink.net,
	agulbra@....unit.no
Subject: [-mm patch] make csum_and_copy_from_user arch independent (was Re: 2.6.21-mm2)

On Wed, May 09, 2007 at 01:23:22AM -0700, Andrew Morton wrote:
> 
> ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.21/2.6.21-mm2/
> 

ERROR: "csum_partial_copy_from_user" [net/rxrpc/af-rxrpc.ko] undefined!

Linking on ARM fails because albeit a generic csum_and_copy_from_user()
function is provided in the case ! _HAVE_ARCH_COPY_AND_CSUM_FROM_USER, the
generic function uses csum_partial_copy_from_user() which is i386 only.

The following patch uses copy_from_user() followed by csum_partial()
to make the function platform independent.

Regards,
Frederik

Signed-off-by: Frederik Deweerdt <frederik.deweerdt@...il.com>

diff --git a/include/net/checksum.h b/include/net/checksum.h
index 1242461..2eebb95 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -30,13 +30,16 @@ static inline
 __wsum csum_and_copy_from_user (const void __user *src, void *dst,
 				      int len, __wsum sum, int *err_ptr)
 {
-	if (access_ok(VERIFY_READ, src, len))
-		return csum_partial_copy_from_user(src, dst, len, sum, err_ptr);
+	if (access_ok(VERIFY_READ, src, len)) {
+		if (copy_from_user(dst, src, len))
+			return -EFAULT;
+		return csum_partial(dst, len, sum);
+	}
 
 	if (len)
 		*err_ptr = -EFAULT;
 
-	return sum;
+	return (__force __wsum)-1; /* invalid checksum */
 }
 #endif
 
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