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

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Message-ID: <20250724220853.1969954-1-aurelien@aurel32.net>
Date: Fri, 25 Jul 2025 00:08:52 +0200
From: Aurelien Jarno <aurelien@...el32.net>
To: linux-kernel@...r.kernel.org,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Clément Léger <cleger@...osinc.com>,
	linux-riscv@...ts.infradead.org (open list:RISC-V ARCHITECTURE)
Cc: Aurelien Jarno <aurelien@...el32.net>
Subject: [PATCH] riscv: uaccess: fix __put_user_nocheck for unaligned accesses

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;						\
-- 
2.47.2