From 1c1d046be692493d00a4831d4fbc266745008e09 Mon Sep 17 00:00:00 2001 From: Arjun Sreedharan Date: Mon, 16 Mar 2015 21:07:47 +0530 Subject: [PATCH] x86/boot: Standardize strcmp() strcmp() is always expected to return 0 when arguments are equal, negative when its first argument @str1 is less than its second argument @str2 and a positive value otherwise. Previously strcmp("a", "b") returned 1. Now it gives -1, as it is supposed to. Until now this bug never triggered, because all uses for strcmp() in the boot code tested for nonzero: triton:~/tip> git grep strcmp arch/x86/boot/ arch/x86/boot/boot.h:int strcmp(const char *str1, const char *str2); arch/x86/boot/edd.c: if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) { arch/x86/boot/edd.c: else if (!strcmp(eddarg, "off")) arch/x86/boot/edd.c: else if (!strcmp(eddarg, "on")) should in the future strcmp() be used in a comparative way in the boot code, it might have led to (not so subtle) bugs. Signed-off-by: Arjun Sreedharan Signed-off-by: Borislav Petkov Cc: H. Peter Anvin Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1426520267-1803-1-git-send-email-arjun024@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/boot/string.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c index 493f3fd9f139..318b8465d302 100644 --- a/arch/x86/boot/string.c +++ b/arch/x86/boot/string.c @@ -30,7 +30,7 @@ int strcmp(const char *str1, const char *str2) int delta = 0; while (*s1 || *s2) { - delta = *s2 - *s1; + delta = *s1 - *s2; if (delta) return delta; s1++;