linux-kernel - [PATCH 5.15 05/45] of: fdt: fix off-by-one error in unflatten_dt

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Message-Id: <20220921153647.090875235@linuxfoundation.org>
Date:   Wed, 21 Sep 2022 17:45:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sergey Shtylyov <s.shtylyov@....ru>,
        Rob Herring <robh@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 05/45] of: fdt: fix off-by-one error in unflatten_dt_nodes()

From: Sergey Shtylyov <s.shtylyov@....ru>

[ Upstream commit 2f945a792f67815abca26fa8a5e863ccf3fa1181 ]

Commit 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
forgot to fix up the depth check in the loop body in unflatten_dt_nodes()
which makes it possible to overflow the nps[] buffer...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Fixes: 78c44d910d3e ("drivers/of: Fix depth when unflattening devicetree")
Signed-off-by: Sergey Shtylyov <s.shtylyov@....ru>
Signed-off-by: Rob Herring <robh@...nel.org>
Link: https://lore.kernel.org/r/7c354554-006f-6b31-c195-cdfe4caee392@omp.ru
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/of/fdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index d245628b15dd..338171c978cc 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -313,7 +313,7 @@ static int unflatten_dt_nodes(const void *blob,
 	for (offset = 0;
 	     offset >= 0 && depth >= initial_depth;
 	     offset = fdt_next_node(blob, offset, &depth)) {
-		if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH))
+		if (WARN_ON_ONCE(depth >= FDT_MAX_DEPTH - 1))
 			continue;
 
 		if (!IS_ENABLED(CONFIG_OF_KOBJ) &&
-- 
2.35.1