From 9be0623d4ce518eead8ea477a4615cb8c3e357d8 Mon Sep 17 00:00:00 2001 From: Jim Mussared Date: Mon, 6 Nov 2023 15:06:28 +1100 Subject: shared/libc/string0: Don't deref args for n==0 case. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit C99 says that strncmp has UB for either string being NULL, so the current behavior is technically correct, but it's an easy fix to handle this case correctly. 7.1.4: "unless explicitly stated otherwise in the detailed description... if an argument to a function has ...null pointer.. the behavior is undeļ¬ned". 7.21.1: "Unless explicitly stated otherwise in the description of a particular function in this subclause, pointer arguments on such a call shall still have valid values, as described in 7.1.4". Also make the same change for the minimal version in bare-arm/lib.c. This work was funded through GitHub Sponsors. Signed-off-by: Jim Mussared --- shared/libc/string0.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'shared/libc') diff --git a/shared/libc/string0.c b/shared/libc/string0.c index a3b268e44..3909f70ed 100644 --- a/shared/libc/string0.c +++ b/shared/libc/string0.c @@ -154,7 +154,7 @@ int strcmp(const char *s1, const char *s2) { } int strncmp(const char *s1, const char *s2, size_t n) { - while (*s1 && *s2 && n > 0) { + while (n > 0 && *s1 && *s2) { char c1 = *s1++; // XXX UTF8 get char, next char char c2 = *s2++; // XXX UTF8 get char, next char n--; -- cgit v1.2.3