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Subject[PATCH] arm: fix text section corruption
Date
When CONFIG_CPU_SW_DOMAIN_PAN is enabled, there are 9 registers being
pushed into stack in save_regs, but in fixup it still consider there are
8 registers in stack, which is the case of CONFIG_CPU_SW_DOMAIN_PAN
disabled.
When fixup being executed, -EFAULT will be written to the text section.

In fixup:
mov r4, #-EFAULT
/*
* When CONFIG_CPU_SW_DOMAIN_PAN enabled, r5 will load the value stored by
* lr in save_regs, which is the address of instruction in text section.
*/
ldr r5, [sp,#8*4] @err_ptr
/*
* This will write -EFAULT(0xfffffff2) to r5, which points to text section
* now, and when function returns, it will use 0xfffffff2 as an
* instruction, then undefined instruction occurs.
*/
str r4, [r5]

Signed-off-by: Ji Zhang <ji.zhang@mediatek.com>
---
arch/arm/lib/csumpartialcopyuser.S | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/arm/lib/csumpartialcopyuser.S b/arch/arm/lib/csumpartialcopyuser.S
index 1712f13..b83fdc0 100644
--- 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
--
1.9.1
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