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kernel: add stack canary to libc partition

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User mode needs to be able to read this value in
compiler generated function prologues/epilogues.

Special handling in init.c for arches that use
_data_copy. This happens before _Cstart() gets
called. We need to make sure that the compiler
stack canary checks in _data_copy itself do not
fail.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2019-02-21 15:02:22 -08:00 • committed by Anas Nashif
commit 01100eadb8
2 changed files with 31 additions and 6 deletions
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7
kernel/compiler_stack_protect.c
View file

@ -22,6 +22,7 @@
#include <toolchain.h>
#include <linker/sections.h>
#include <kernel.h>
#include <app_memory/app_memdomain.h>
/**
*
@ -45,7 +46,11 @@ void FUNC_NORETURN _StackCheckHandler(void)
* Symbol referenced by GCC compiler generated code for canary value.
* The canary value gets initialized in _Cstart().
*/
void __noinit *__stack_chk_guard;
#ifdef CONFIG_APP_SHARED_MEM
K_APP_DMEM(z_libc_partition) uintptr_t __stack_chk_guard;
#else
__noinit uintptr_t __stack_chk_guard;
#endif
/**
*

30
kernel/init.c
View file

@ -159,6 +159,10 @@ void _bss_zero(void)
#endif
}
#ifdef CONFIG_STACK_CANARIES
extern volatile uintptr_t __stack_chk_guard;
#endif /* CONFIG_STACK_CANARIES */
#ifdef CONFIG_XIP
/**
@ -187,9 +191,29 @@ void _data_copy(void)
data_copy_xip_relocation();
#endif /* CONFIG_CODE_DATA_RELOCATION */
#ifdef CONFIG_APP_SHARED_MEM
#ifdef CONFIG_STACK_CANARIES
/* stack canary checking is active for all C functions.
* __stack_chk_guard is some uninitialized value living in the
* app shared memory sections. Preserve it, and don't make any
* function calls to perform the memory copy. The true canary
* value gets set later in _Cstart().
*/
uintptr_t guard_copy = __stack_chk_guard;
u8_t *src = (u8_t *)&_app_smem_rom_start;
u8_t *dst = (u8_t *)&_app_smem_start;
u32_t count = (u32_t)&_app_smem_end - (u32_t)&_app_smem_start;
guard_copy = __stack_chk_guard;
while (count > 0) {
*(dst++) = *(src++);
count--;
}
__stack_chk_guard = guard_copy;
#else
(void)memcpy(&_app_smem_start, &_app_smem_rom_start,
((u32_t) &_app_smem_end - (u32_t) &_app_smem_start));
#endif
#endif /* CONFIG_STACK_CANARIES */
#endif /* CONFIG_APP_SHARED_MEM */
}
#endif
@ -439,10 +463,6 @@ sys_rand32_fallback:
return sys_rand32_get();
}
#ifdef CONFIG_STACK_CANARIES
extern uintptr_t __stack_chk_guard;
#endif /* CONFIG_STACK_CANARIES */
/**
*
* @brief Initialize kernel