linux-kernel - [PATCH] lib/test_stackinit: Expand variable size for correct testing

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Date:   Tue, 15 Feb 2022 08:59:10 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH] lib/test_stackinit: Expand variable size for correct testing

The pre-case switch variable was too small for the test to detect
missing initialization. Expand the variable so the test will start to
(expectedly) fail again.

Cc: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 lib/test_stackinit.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/test_stackinit.c b/lib/test_stackinit.c
index a3c74e6a21ff..70bb4f7dea38 100644
--- a/lib/test_stackinit.c
+++ b/lib/test_stackinit.c
@@ -398,7 +398,7 @@ static int noinline __leaf_switch_none(int path, bool fill)
 		 * This is intentionally unreachable. To silence the
 		 * warning, build with -Wno-switch-unreachable
 		 */
-		uint64_t var;
+		uint64_t var[10];
 
 	case 1:
 		target_start = &var;
@@ -423,8 +423,8 @@ static int noinline __leaf_switch_none(int path, bool fill)
 		memcpy(check_buf, target_start, target_size);
 		break;
 	default:
-		var = 5;
-		return var & forced_mask;
+		var[1] = 5;
+		return var[1] & forced_mask;
 	}
 	return 0;
 }
-- 
2.30.2