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Subject[PATCH V2] ZBOOT: fix stack protector in compressed boot phase
Date
Call __stack_chk_guard_setup() in decompress_kernel() is too late that
stack checking always fails for decompress_kernel() itself. So remove
__stack_chk_guard_setup() and initialize __stack_chk_guard before we
call decompress_kernel().

Original code comes from ARM but also used for MIPS and SH, so fix them
together. If without this fix, compressed booting of these archs will
fail because stack checking is enabled by default (>=4.16).

V2: Fix build on ARM.

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhc@lemote.com>
---
arch/arm/boot/compressed/head.S | 4 ++++
arch/arm/boot/compressed/misc.c | 7 -------
arch/mips/boot/compressed/decompress.c | 7 -------
arch/mips/boot/compressed/head.S | 4 ++++
arch/sh/boot/compressed/head_32.S | 4 ++++
arch/sh/boot/compressed/head_64.S | 4 ++++
arch/sh/boot/compressed/misc.c | 7 -------
7 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 45c8823..bae1fc6 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -547,6 +547,10 @@ not_relocated: mov r0, #0
bic r4, r4, #1
blne cache_on

+ ldr r0, =__stack_chk_guard
+ ldr r1, =0x000a0dff
+ str r1, [r0]
+
/*
* The C runtime environment should now be setup sufficiently.
* Set up some pointers, and start decompressing.
diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
index 16a8a80..e518ef5 100644
--- a/arch/arm/boot/compressed/misc.c
+++ b/arch/arm/boot/compressed/misc.c
@@ -130,11 +130,6 @@ asmlinkage void __div0(void)

unsigned long __stack_chk_guard;

-void __stack_chk_guard_setup(void)
-{
- __stack_chk_guard = 0x000a0dff;
-}
-
void __stack_chk_fail(void)
{
error("stack-protector: Kernel stack is corrupted\n");
@@ -150,8 +145,6 @@ decompress_kernel(unsigned long output_start, unsigned long free_mem_ptr_p,
{
int ret;

- __stack_chk_guard_setup();
-
output_data = (unsigned char *)output_start;
free_mem_ptr = free_mem_ptr_p;
free_mem_end_ptr = free_mem_ptr_end_p;
diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
index fdf99e9..5ba431c 100644
--- a/arch/mips/boot/compressed/decompress.c
+++ b/arch/mips/boot/compressed/decompress.c
@@ -78,11 +78,6 @@ void error(char *x)

unsigned long __stack_chk_guard;

-void __stack_chk_guard_setup(void)
-{
- __stack_chk_guard = 0x000a0dff;
-}
-
void __stack_chk_fail(void)
{
error("stack-protector: Kernel stack is corrupted\n");
@@ -92,8 +87,6 @@ void decompress_kernel(unsigned long boot_heap_start)
{
unsigned long zimage_start, zimage_size;

- __stack_chk_guard_setup();
-
zimage_start = (unsigned long)(&__image_begin);
zimage_size = (unsigned long)(&__image_end) -
(unsigned long)(&__image_begin);
diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
index 409cb48..00d0ee0 100644
--- a/arch/mips/boot/compressed/head.S
+++ b/arch/mips/boot/compressed/head.S
@@ -32,6 +32,10 @@ start:
bne a2, a0, 1b
addiu a0, a0, 4

+ PTR_LA a0, __stack_chk_guard
+ PTR_LI a1, 0x000a0dff
+ sw a1, 0(a0)
+
PTR_LA a0, (.heap) /* heap address */
PTR_LA sp, (.stack + 8192) /* stack address */

diff --git a/arch/sh/boot/compressed/head_32.S b/arch/sh/boot/compressed/head_32.S
index 7bb1681..a3fdb05 100644
--- a/arch/sh/boot/compressed/head_32.S
+++ b/arch/sh/boot/compressed/head_32.S
@@ -76,6 +76,10 @@ l1:
mov.l init_stack_addr, r0
mov.l @r0, r15

+ mov.l __stack_chk_guard, r0
+ mov #0x000a0dff, r1
+ mov.l r1, @r0
+
/* Decompress the kernel */
mov.l decompress_kernel_addr, r0
jsr @r0
diff --git a/arch/sh/boot/compressed/head_64.S b/arch/sh/boot/compressed/head_64.S
index 9993113..8b4d540 100644
--- a/arch/sh/boot/compressed/head_64.S
+++ b/arch/sh/boot/compressed/head_64.S
@@ -132,6 +132,10 @@ startup:
addi r22, 4, r22
bne r22, r23, tr1

+ movi datalabel __stack_chk_guard, r0
+ movi 0x000a0dff, r1
+ st.l r0, 0, r1
+
/*
* Decompress the kernel.
*/
diff --git a/arch/sh/boot/compressed/misc.c b/arch/sh/boot/compressed/misc.c
index 627ce8e..fe4c079 100644
--- a/arch/sh/boot/compressed/misc.c
+++ b/arch/sh/boot/compressed/misc.c
@@ -106,11 +106,6 @@ static void error(char *x)

unsigned long __stack_chk_guard;

-void __stack_chk_guard_setup(void)
-{
- __stack_chk_guard = 0x000a0dff;
-}
-
void __stack_chk_fail(void)
{
error("stack-protector: Kernel stack is corrupted\n");
@@ -130,8 +125,6 @@ void decompress_kernel(void)
{
unsigned long output_addr;

- __stack_chk_guard_setup();
-
#ifdef CONFIG_SUPERH64
output_addr = (CONFIG_MEMORY_START + 0x2000);
#else
--
2.7.0
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