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

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Message-Id: <5f6e80c4b0c7f7f0b6211900847a247cdaad753c.1479398226.git.jpoimboe@redhat.com>
Date:   Thu, 17 Nov 2016 09:57:24 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Vince Weaver <vincent.weaver@...ne.edu>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        davej@...emonkey.org.uk, dvyukov@...gle.com,
        Stephane Eranian <eranian@...il.com>
Subject: [PATCH 2/2] dumpstack: prevent KASAN false positive warnings

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@...hat.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