[PATCH] powerpc/32: fix again csum_partial_copy_generic()

[PATCH] powerpc/32: fix again csum_partial_copy_generic()

[Christophe Leroy]

commit 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()") introduced a bug when destination
address is odd and len is lower than cacheline size.

In that case the resulting csum value doesn't have to be rotated one
byte because the cache-aligned copy part is skipped so no alignment
is performed.

Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
based on copy_tofrom_user()")
Cc: stable@vger.kernel.org

Reported-by: Alessio Igor Bogani <alessio.bogani@elettra.eu>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Tested-by: Alessio Igor Bogani <alessio.bogani@elettra.eu>
---
 arch/powerpc/lib/checksum_32.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index 0a57fe6..aa8214f 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -127,18 +127,19 @@ _GLOBAL(csum_partial_copy_generic)
 	stw	r7,12(r1)
 	stw	r8,8(r1)
 
-	rlwinm	r0,r4,3,0x8
-	rlwnm	r6,r6,r0,0,31	/* odd destination address: rotate one byte */
-	cmplwi	cr7,r0,0	/* is destination address even ? */
 	addic	r12,r6,0
 	addi	r6,r4,-4
 	neg	r0,r4
 	addi	r4,r3,-4
 	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
+	crset	4*cr7+eq
 	beq	58f
 
 	cmplw	0,r5,r0			/* is this more than total to do? */
 	blt	63f			/* if not much to do */
+	rlwinm	r7,r6,3,0x8
+	rlwnm	r12,r12,r7,0,31	/* odd destination address: rotate one byte */
+	cmplwi	cr7,r7,0	/* is destination address even ? */
 	andi.	r8,r0,3			/* get it word-aligned first */
 	mtctr	r8
 	beq+	61f
-- 
2.1.0

Re: powerpc/32: fix again csum_partial_copy_generic()

[Michael Ellerman]

On Fri, 2016-26-08 at 14:45:13 UTC, Christophe Leroy wrote:
> commit 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic()
> based on copy_tofrom_user()") introduced a bug when destination
> address is odd and len is lower than cacheline size.
> 
> In that case the resulting csum value doesn't have to be rotated one
> byte because the cache-aligned copy part is skipped so no alignment
> is performed.
> 
> Fixes: 7aef4136566b0 ("powerpc32: rewrite csum_partial_copy_generic() based on copy_tofrom_user()")
> Cc: stable@vger.kernel.org
> Reported-by: Alessio Igor Bogani <alessio.bogani@elettra.eu>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> Tested-by: Alessio Igor Bogani <alessio.bogani@elettra.eu>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/8540571e01f973d321b0821f4f

cheers