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Date: Wed, 12 Jul 2017 15:44:21 +0100
From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
To: linux-arm-kernel@...ts.infradead.org,
kernel-hardening@...ts.openwall.com
Cc: mark.rutland@....com,
labbott@...oraproject.org,
will.deacon@....com,
dave.martin@....com,
catalin.marinas@....com,
Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: [RFC PATCH 08/10] arm64/kernel: dump entire stack if sp points elsewhere
Before adding handling for out of bounds stack accesses, update the
stack dumping logic to disregard regs->sp if it does not point into
the task stack anymore, and simply dump the entire stack instead.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
arch/arm64/kernel/traps.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index c7c7088097be..017c92b2d707 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -257,7 +257,14 @@ static int __die(const char *str, int err, struct pt_regs *regs)
end_of_stack(tsk));
if (!user_mode(regs)) {
- dump_mem(KERN_EMERG, "Stack: ", regs->sp,
+ u64 task_sp = regs->sp;
+
+ /* dump the entire stack if sp no longer points into it */
+ if (task_sp < (u64)task_stack_page(tsk) ||
+ task_sp > (u64)task_stack_page(tsk) + THREAD_SIZE)
+ task_sp = (u64)task_stack_page(tsk);
+
+ dump_mem(KERN_EMERG, "Stack: ", task_sp,
THREAD_SIZE + (unsigned long)task_stack_page(tsk));
dump_backtrace(regs, tsk);
dump_instr(KERN_EMERG, regs);
--
2.9.3
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