[PATCH 2/2] dumpstack: prevent KASAN false positive warnings

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: x86@kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>,
	Vince Weaver <vincent.weaver@maine.edu>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	davej@codemonkey.org.uk, dvyukov@google.com,
	Stephane Eranian <eranian@gmail.com>
Subject: [PATCH 2/2] dumpstack: prevent KASAN false positive warnings
Date: Thu, 17 Nov 2016 09:57:24 -0600	[thread overview]
Message-ID: <5f6e80c4b0c7f7f0b6211900847a247cdaad753c.1479398226.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <20161116130337.GT3142@twins.programming.kicks-ass.net>
In-Reply-To: <61939c0b2b2d63ce97ba59cba3b00fd47c2962cf.1479398226.git.jpoimboe@redhat.com>

The oops stack dump code scans the entire stack, which can cause KASAN
"stack-out-of-bounds" false positive warnings.  Tell KASAN to ignore it.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
 arch/x86/kernel/dumpstack.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index 9b7cf5c..85f854b 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -112,7 +112,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
 		for (; stack < stack_info.end; stack++) {
 			unsigned long real_addr;
 			int reliable = 0;
-			unsigned long addr = *stack;
+			unsigned long addr = READ_ONCE_NOCHECK(*stack);
 			unsigned long *ret_addr_p =
 				unwind_get_return_address_ptr(&state);
 
-- 
2.7.4
