[PATCH 4.9 063/207] x86: Increase exception stack sizes

Greg Kroah-Hartman
2021-11-24T12:21:38Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 7fae4c24a2b84a66c7be399727aca11e7a888462 ]

It turns out that a single page of stack is trivial to overflow with
all the tracing gunk enabled. Raise the exception stacks to 2 pages,
which is still half the interrupt stacks, which are at 4 pages.

Reported-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YUIO9Ye98S5Eb68w@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/include/asm/page_64_types.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/page_64_types.h b/arch/x86/include/asm/page_64_types.h
index 390fdd39e0e21..5a69eee673536 100644
--- a/arch/x86/include/asm/page_64_types.h
+++ b/arch/x86/include/asm/page_64_types.h
@@ -19,7 +19,7 @@
#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
#define CURRENT_MASK (~(THREAD_SIZE - 1))

-#define EXCEPTION_STACK_ORDER (0 + KASAN_STACK_ORDER)
+#define EXCEPTION_STACK_ORDER (1 + KASAN_STACK_ORDER)
#define EXCEPTION_STKSZ (PAGE_SIZE << EXCEPTION_STACK_ORDER)

#define DEBUG_STACK_ORDER (EXCEPTION_STACK_ORDER + 1)
--
2.33.0