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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Lvqiang Huang <Lvqiang.Huang@spreadtrum.com>,
        Chunyan Zhang <zhang.lyra@gmail.com>,
        Russell King <rmk+kernel@armlinux.org.uk>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 05/34] ARM: 8731/1: Fix csum_partial_copy_from_user() stack mismatch
Date:   Fri,  2 Mar 2018 09:51:01 +0100
Message-Id: <20180302084436.333276338@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chunyan Zhang <zhang.lyra@gmail.com>


[ Upstream commit 36b0cb84ee858f02c256d26f0cb4229c78e3399e ]

An additional 'ip' will be pushed to the stack, for restoring the
DACR later, if CONFIG_CPU_SW_DOMAIN_PAN defined.

However, the fixup still get the err_ptr by add #8*4 to sp, which
results in the fact that the code area pointed by the LR will be
overwritten, or the kernel will crash if CONFIG_DEBUG_RODATA is enabled.

This patch fixes the stack mismatch.

Fixes: a5e090acbf54 ("ARM: software-based priviledged-no-access support")
Signed-off-by: Lvqiang Huang <Lvqiang.Huang@spreadtrum.com>
Signed-off-by: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm/lib/csumpartialcopyuser.S |    4 ++++
 1 file changed, 4 insertions(+)

--- a/arch/arm/lib/csumpartialcopyuser.S
+++ b/arch/arm/lib/csumpartialcopyuser.S
@@ -85,7 +85,11 @@
 		.pushsection .text.fixup,"ax"
 		.align	4
 9001:		mov	r4, #-EFAULT
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+		ldr	r5, [sp, #9*4]		@ *err_ptr
+#else
 		ldr	r5, [sp, #8*4]		@ *err_ptr
+#endif
 		str	r4, [r5]
 		ldmia	sp, {r1, r2}		@ retrieve dst, len
 		add	r2, r2, r1