[PATCH v2] x86/traps: do not hash pointers in handle_stack_overflow()

From: Eric Dumazet
Date: Fri Feb 07 2020 - 10:49:31 EST


Mangling stack pointers in handle_stack_overflow() is moot,
as registers (including RSP/RBP) are clear anyway.

Also switch to pr_emerg() as suggested by Thomas.

BUG: stack guard page was hit at 0000000063381e80 (stack is 000000008edc5696..0000000012256c50)
kernel stack overflow (double-fault): 0000 [#1] PREEMPT SMP KASAN
...
RSP: 0018:ffffc90002c1ffc0 EFLAGS: 00010802
RAX: 1ffff11004a0094c RBX: ffff888025004180 RCX: c9d82d1007bb146c
RDX: dffffc0000000000 RSI: ffff888025004a40 RDI: ffff888025004180
RBP: ffffc90002c201c0 R08: dffffc0000000000 R09: fffffbfff1405915
R10: fffffbfff1405915 R11: 0000000000000000 R12: ffff888025004a60
R13: ffff888025004a10 R14: c9d82d1007bb146c R15: ffff888025004180
...

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/traps.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 6ef00eb6fbb925e86109f86845e2b3ccef4023ec..318df13e267638c4888f1c3f611aff34818b3bd2 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -296,7 +296,7 @@ __visible void __noreturn handle_stack_overflow(const char *message,
struct pt_regs *regs,
unsigned long fault_address)
{
- printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n",
+ pr_emerg("BUG: stack guard page was hit at %px (stack is %px..%px)\n",
(void *)fault_address, current->stack,
(char *)current->stack + THREAD_SIZE - 1);
die(message, regs, 0);
--
2.25.0.341.g760bfbb309-goog