linux-kernel - [PATCH] x86/signal: Fix the value returned by strict_sas

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Date:   Sat, 14 Jan 2023 18:33:09 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH] x86/signal: Fix the value returned by strict_sas_size()

Functions used with __setup() return 1 when the argument has been
successfully parsed.

Reverse the returned value so that 1 is returned when kstrtobool() is
successful (i.e. returns 0)

Fixes: 3aac3ebea08f ("x86/signal: Implement sigaltstack size validation")
Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
This patch is completely speculative. Review with care!

My understanding of these __setup() functions is that returning 1 or 0
does not change much anyway.

I spot it and found it spurious while looking at something else.
Even if the output is not perfect, you'll get the idea with:
   git grep -B2 -A10 retu.*kstrtobool | grep __setup -B10
---
 arch/x86/kernel/signal.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 1504eb8d25aa..004cb30b7419 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -360,7 +360,7 @@ static bool strict_sigaltstack_size __ro_after_init = false;
 
 static int __init strict_sas_size(char *arg)
 {
-	return kstrtobool(arg, &strict_sigaltstack_size);
+	return kstrtobool(arg, &strict_sigaltstack_size) == 0;
 }
 __setup("strict_sas_size", strict_sas_size);
 
-- 
2.34.1