linux-kernel - [PATCH] ARC: Fix array-out-of-bounds issue in tlb overlap handler

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Message-Id: <1380203182-5982-1-git-send-email-mjonker@synopsys.com>
Date:	Thu, 26 Sep 2013 15:46:22 +0200
From:	Mischa Jonker <Mischa.Jonker@...opsys.com>
To:	Vineet.Gupta1@...opsys.com, linux-kernel@...r.kernel.org,
	arc-linux-dev@...opsys.com
Cc:	Mischa Jonker <Mischa.Jonker@...opsys.com>
Subject: [PATCH] ARC: Fix array-out-of-bounds issue in tlb overlap handler

Even after fixing the issue, GCC 4.8 still complains with a warning,
but with the fix, I think it's a false positive. Therefore I have
also added a #pragma to ignore the warning.

Signed-off-by: Mischa Jonker <mjonker@...opsys.com>
---
 arch/arc/mm/tlb.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index 129af50..5af7c98 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -635,13 +635,20 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
 			continue;
 
 		/* Scan the set for duplicate ways: needs a nested loop */
-		for (way = 0; way < mmu->ways; way++) {
+		for (way = 0; way < (mmu->ways - 1); way++) {
 			if (!pd0[way])
 				continue;
 
 			for (n = way + 1; n < mmu->ways; n++) {
+/*
+ * GCC 4.8 does not understand that way < (mmu->ways - 1), and as such
+ * n < mmu->ways. So, ignore the warning
+ */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Warray-bounds"
 				if ((pd0[way] & PAGE_MASK) ==
 				    (pd0[n] & PAGE_MASK)) {
+#pragma GCC diagnostic pop
 
 					if (dup_pd_verbose) {
 						pr_info("Duplicate PD's @"
-- 
1.7.9.5

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