[PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned accesses

[PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned accesses

[Aurelien Jarno]

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@aurel32.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;						\
-- 
2.47.2

Re: [PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned accesses

[Alexandre Ghiti]

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@aurel32.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@rivosinc.com>

Thanks,

Alex

Re: [PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned accesses

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (for-next)
by Alexandre Ghiti <alexghiti@rivosinc.com>:

On Fri, 25 Jul 2025 00:08:52 +0200 you 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.
> 
> [...]

Here is the summary with links:
  - riscv: uaccess: fix __put_user_nocheck for unaligned accesses
    https://git.kernel.org/riscv/c/a10ce19d93c9

You are awesome, thank you!
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