We use Kconfig to select the kernel stack size, doubling the default size if KASAN is enabled.

But that actually only works if KASAN is selected from the beginning, meaning that if KASAN config is added later (for example using menuconfig), CONFIG_THREAD_SIZE_ORDER won't be updated, keeping the default size, which is not enough for KASAN as reported in [1].

So fix this by moving the logic to compute the right kernel stack into a header.

Fixes: a7555f6b62e7 ("riscv: stack: Add config of thread stack size") Reported-by: syzbot+ba9eac24453387a9d502@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000eb301906222aadc2@google.com/ [1] Cc: stable@vger.kernel.org Signed-off-by: Alexandre Ghiti alexghiti@rivosinc.com --- arch/riscv/Kconfig | 3 +-- arch/riscv/include/asm/thread_info.h | 7 ++++++- 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index ccbfd28f4982..b65846d02622 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -759,8 +759,7 @@ config IRQ_STACKS config THREAD_SIZE_ORDER int "Kernel stack size (in power-of-two numbers of page size)" if VMAP_STACK && EXPERT range 0 4 - default 1 if 32BIT && !KASAN - default 3 if 64BIT && KASAN + default 1 if 32BIT default 2 help Specify the Pages of thread stack size (from 4KB to 64KB), which also diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h index fca5c6be2b81..385b43211a71 100644 --- a/arch/riscv/include/asm/thread_info.h +++ b/arch/riscv/include/asm/thread_info.h @@ -13,7 +13,12 @@ #include <linux/sizes.h>

/* thread information allocation */ -#define THREAD_SIZE_ORDER CONFIG_THREAD_SIZE_ORDER +#ifdef CONFIG_KASAN +#define KASAN_STACK_ORDER 1 +#else +#define KASAN_STACK_ORDER 0 +#endif +#define THREAD_SIZE_ORDER (CONFIG_THREAD_SIZE_ORDER + KASAN_STACK_ORDER) #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)

/*