linux-kernel - [PATCH] m68k: string: Make char intermediate in strcmp() signed

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Date:   Thu, 15 Dec 2022 14:30:04 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "Jason A . Donenfeld" <Jason@...c4.com>
Cc:     linux-m68k@...ts.linux-m68k.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH] m68k: string: Make char intermediate in strcmp() signed

Since char became unsigned, strcmp() always returns a positive number.

"res" is used to store a byte difference, so it should be signed.

Fixes: 3bc753c06dd02a35 ("kbuild: treat char as always unsigned")
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
---
See "Re: [PATCH v9] kallsyms: Add self-test facility"
https://lore.kernel.org/r/CAMuHMdWM6+pC3yUqy+hHRrAf1BCz2sz1KQv2zxS+Wz-639X-aA@mail.gmail.com

I'm wondering how many surprises like this are still hidden...
---
 arch/m68k/include/asm/string.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/m68k/include/asm/string.h b/arch/m68k/include/asm/string.h
index f759d944c4499404..b8f4ae19e8f6ee2c 100644
--- a/arch/m68k/include/asm/string.h
+++ b/arch/m68k/include/asm/string.h
@@ -42,7 +42,7 @@ static inline char *strncpy(char *dest, const char *src, size_t n)
 #define __HAVE_ARCH_STRCMP
 static inline int strcmp(const char *cs, const char *ct)
 {
-	char res;
+	signed char res;
 
 	asm ("\n"
 		"1:	move.b	(%0)+,%2\n"	/* get *cs */
-- 
2.25.1