linux-kernel - Re: [PATCH] riscv: uaccess: fix __put_user

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Message-ID: <fa6f5e3c-3452-41ff-ab81-60f5f31ff797@ghiti.fr>
Date: Fri, 25 Jul 2025 15:42:15 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Aurelien Jarno <aurelien@...el32.net>, linux-kernel@...r.kernel.org,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Clément Léger <cleger@...osinc.com>,
 "open list:RISC-V ARCHITECTURE" <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned
 accesses

Hi Aurélien,

On 7/25/25 00:08, Aurelien Jarno wrote:
> The type of the value to write should be determined by the size of the
> destination, not by the value itself, which may be a constant. This
> aligns the behavior with x86_64, where __typeof__(*(__gu_ptr)) is used
> to infer the correct type.
>
> This fixes an issue in put_cmsg, which was only writing 4 out of 8
> bytes to the cmsg_len field, causing the glibc tst-socket-timestamp test
> to fail.
>
> Fixes: ca1a66cdd685 ("riscv: uaccess: do not do misaligned accesses in get/put_user()")
> Signed-off-by: Aurelien Jarno <aurelien@...el32.net>
> ---
>   arch/riscv/include/asm/uaccess.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/uaccess.h b/arch/riscv/include/asm/uaccess.h
> index b88a6218b7f24..22e3f52a763d1 100644
> --- a/arch/riscv/include/asm/uaccess.h
> +++ b/arch/riscv/include/asm/uaccess.h
> @@ -311,7 +311,7 @@ do {								\
>   do {								\
>   	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) &&	\
>   	    !IS_ALIGNED((uintptr_t)__gu_ptr, sizeof(*__gu_ptr))) {	\
> -		__inttype(x) ___val = (__inttype(x))x;			\
> +		__typeof__(*(__gu_ptr)) ___val = (x);		\
>   		if (__asm_copy_to_user_sum_enabled(__gu_ptr, &(___val), sizeof(*__gu_ptr))) \
>   			goto label;				\
>   		break;						\


Thanks for catching this (I will add the glibc testsuite to our CI).

Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex