Re: [PATCH] powerpc/kasan: Force thread size increase with KASAN
On Thu, 2 Jun 2022 00:31:14 +1000, Michael Ellerman wrote: > KASAN causes increased stack usage, which can lead to stack overflows. > > The logic in Kconfig to suggest a larger default doesn't work if a user > has CONFIG_EXPERT enabled and has an existing .config with a smaller > value. > > Follow the lead of x86 and arm64, and force the thread size to be > increased when KASAN is enabled. > > [...] Applied to powerpc/fixes. [1/1] powerpc/kasan: Force thread size increase with KASAN https://git.kernel.org/powerpc/c/3e8635fb2e072672cbc650989ffedf8300ad67fb cheers
Re: [PATCH] powerpc/kasan: Force thread size increase with KASAN
Le 01/06/2022 à 16:31, Michael Ellerman a écrit :
> KASAN causes increased stack usage, which can lead to stack overflows.
>
> The logic in Kconfig to suggest a larger default doesn't work if a user
> has CONFIG_EXPERT enabled and has an existing .config with a smaller
> value.
>
> Follow the lead of x86 and arm64, and force the thread size to be
> increased when KASAN is enabled.
>
> That also has the effect of enlarging the stack for 64-bit KASAN builds,
> which is also desirable.
>
> Fixes: edbadaf06710 ("powerpc/kasan: Fix stack overflow by increasing
> THREAD_SHIFT")
> Reported-by: Erhard Furtner
> Reported-by: Christophe Leroy
> Signed-off-by: Michael Ellerman
> ---
> arch/powerpc/Kconfig | 1 -
> arch/powerpc/include/asm/thread_info.h | 9 +++--
> 2 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 54dbbb1d4b36..b1760d615bb7 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -790,7 +790,6 @@ config THREAD_SHIFT
> range 13 15
> default "15" if PPC_256K_PAGES
> default "14" if PPC64
> - default "14" if KASAN
> default "13"
> help
> Used to define the stack size. The default is almost always what you
> diff --git a/arch/powerpc/include/asm/thread_info.h
> b/arch/powerpc/include/asm/thread_info.h
> index 125328d1b980..c9735f93f8e6 100644
> --- a/arch/powerpc/include/asm/thread_info.h
> +++ b/arch/powerpc/include/asm/thread_info.h
> @@ -14,12 +14,17 @@
>
> #ifdef __KERNEL__
>
> -#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
> -#define THREAD_SHIFT PAGE_SHIFT
> +#ifdef CONFIG_KASAN
> +#define THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1)
> #else
> #define THREAD_SHIFTCONFIG_THREAD_SHIFT
> #endif
>
> +#if defined(CONFIG_VMAP_STACK) && THREAD_SHIFT < PAGE_SHIFT
> +#undef THREAD_SHIFT
I dislike this undef.
I would was done
#ifdef CONFIG_KASAN
#define MIN_THREAD_SHIFT(CONFIG_THREAD_SHIFT + 1)
#else
#define MIN_THREAD_SHIFTCONFIG_THREAD_SHIFT
#endif
#if defined(CONFIG_VMAP_STACK) && MIN_THREAD_SHIFT < PAGE_SHIFT
#define THREAD_SHIFTPAGE_SHIFT
#else
#define THREAD_SHIFTMIN_THREAD_SHIFT
#endif
> +#define THREAD_SHIFT PAGE_SHIFT
> +#endif
> +
> #define THREAD_SIZE (1 << THREAD_SHIFT)
>
> /*
[PATCH] powerpc/kasan: Force thread size increase with KASAN
KASAN causes increased stack usage, which can lead to stack overflows.
The logic in Kconfig to suggest a larger default doesn't work if a user
has CONFIG_EXPERT enabled and has an existing .config with a smaller
value.
Follow the lead of x86 and arm64, and force the thread size to be
increased when KASAN is enabled.
That also has the effect of enlarging the stack for 64-bit KASAN builds,
which is also desirable.
Fixes: edbadaf06710 ("powerpc/kasan: Fix stack overflow by increasing
THREAD_SHIFT")
Reported-by: Erhard Furtner
Reported-by: Christophe Leroy
Signed-off-by: Michael Ellerman
---
arch/powerpc/Kconfig | 1 -
arch/powerpc/include/asm/thread_info.h | 9 +++--
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 54dbbb1d4b36..b1760d615bb7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -790,7 +790,6 @@ config THREAD_SHIFT
range 13 15
default "15" if PPC_256K_PAGES
default "14" if PPC64
- default "14" if KASAN
default "13"
help
Used to define the stack size. The default is almost always what you
diff --git a/arch/powerpc/include/asm/thread_info.h
b/arch/powerpc/include/asm/thread_info.h
index 125328d1b980..c9735f93f8e6 100644
--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h
@@ -14,12 +14,17 @@
#ifdef __KERNEL__
-#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
-#define THREAD_SHIFT PAGE_SHIFT
+#ifdef CONFIG_KASAN
+#define THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1)
#else
#define THREAD_SHIFT CONFIG_THREAD_SHIFT
#endif
+#if defined(CONFIG_VMAP_STACK) && THREAD_SHIFT < PAGE_SHIFT
+#undef THREAD_SHIFT
+#define THREAD_SHIFT PAGE_SHIFT
+#endif
+
#define THREAD_SIZE(1 << THREAD_SHIFT)
/*
--
2.35.3
