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From:   WANG Rui <wangrui@loongson.cn>
To:     Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>
Cc:     Jun Yi <yijun@loongson.cn>, Tiezhu Yang <yangtiezhu@loongson.cn>,
        loongarch@lists.linux.dev, linux-kernel@vger.kernel.org,
        WANG Rui <wangrui@loongson.cn>, stable@vger.kernel.org,
        Weihao Li <liweihao@loongson.cn>
Subject: [PATCH] LoongArch: Fix return value underflow in exception path
Date:   Thu, 13 Jul 2023 11:04:53 +0800
Message-ID: <20230713030453.7404-1-wangrui@loongson.cn>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This patch fixes an underflow issue in the return value within the
exception path, specifically at .Llt8 when the remaining length is less
than 8 bytes.

Cc: stable@vger.kernel.org
Fixes: 8941e93ca590 ("LoongArch: Optimize memory ops (memset/memcpy/memmove)")
Reported-by: Weihao Li <liweihao@loongson.cn>
Signed-off-by: WANG Rui <wangrui@loongson.cn>
---
 arch/loongarch/lib/clear_user.S | 3 ++-
 arch/loongarch/lib/copy_user.S  | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/loongarch/lib/clear_user.S b/arch/loongarch/lib/clear_user.S
index fd1d62b244f2..9dcf71719387 100644
--- a/arch/loongarch/lib/clear_user.S
+++ b/arch/loongarch/lib/clear_user.S
@@ -108,6 +108,7 @@ SYM_FUNC_START(__clear_user_fast)
 	addi.d	a3, a2, -8
 	bgeu	a0, a3, .Llt8
 15:	st.d	zero, a0, 0
+	addi.d	a0, a0, 8
 
 .Llt8:
 16:	st.d	zero, a2, -8
@@ -188,7 +189,7 @@ SYM_FUNC_START(__clear_user_fast)
 	_asm_extable 13b, .L_fixup_handle_0
 	_asm_extable 14b, .L_fixup_handle_1
 	_asm_extable 15b, .L_fixup_handle_0
-	_asm_extable 16b, .L_fixup_handle_1
+	_asm_extable 16b, .L_fixup_handle_0
 	_asm_extable 17b, .L_fixup_handle_s0
 	_asm_extable 18b, .L_fixup_handle_s0
 	_asm_extable 19b, .L_fixup_handle_s0
diff --git a/arch/loongarch/lib/copy_user.S b/arch/loongarch/lib/copy_user.S
index b21f6d5d38f5..fecd08cad702 100644
--- a/arch/loongarch/lib/copy_user.S
+++ b/arch/loongarch/lib/copy_user.S
@@ -136,6 +136,7 @@ SYM_FUNC_START(__copy_user_fast)
 	bgeu	a1, a4, .Llt8
 30:	ld.d	t0, a1, 0
 31:	st.d	t0, a0, 0
+	addi.d	a0, a0, 8
 
 .Llt8:
 32:	ld.d	t0, a3, -8
@@ -246,7 +247,7 @@ SYM_FUNC_START(__copy_user_fast)
 	_asm_extable 30b, .L_fixup_handle_0
 	_asm_extable 31b, .L_fixup_handle_0
 	_asm_extable 32b, .L_fixup_handle_0
-	_asm_extable 33b, .L_fixup_handle_1
+	_asm_extable 33b, .L_fixup_handle_0
 	_asm_extable 34b, .L_fixup_handle_s0
 	_asm_extable 35b, .L_fixup_handle_s0
 	_asm_extable 36b, .L_fixup_handle_s0
-- 
2.41.0