fix misaligned read on early string termination in strchr

this could actually cause rare crashes in the case where a short
string is located at the end of a page and the following page is not
readable, and in fact this was seen in gcc compiling certain files.

diff --git a/src/string/strchr.c b/src/string/strchr.c
index 2fe0338..d3563f1 100644 (file)
--- a/src/string/strchr.c
+++ b/src/string/strchr.c
@@ -15,8 +15,9 @@ char *strchr(const char *s, int c)
        c = (unsigned char)c;
        if (!c) return (char *)s + strlen(s);
 
        c = (unsigned char)c;
        if (!c) return (char *)s + strlen(s);
 

-       for (; ((uintptr_t)s & ALIGN) && *s; s++)
+       for (; ((uintptr_t)s & ALIGN); s++)

                if (*(unsigned char *)s == c) return (char *)s;
                if (*(unsigned char *)s == c) return (char *)s;

+               else if (!*s) return 0;

        k = ONES * c;
        for (w = (void *)s; !HASZERO(*w) && !HASZERO(*w^k); w++);
        for (s = (void *)w; *s; s++)
        k = ONES * c;
        for (w = (void *)s; !HASZERO(*w) && !HASZERO(*w^k); w++);
        for (s = (void *)w; *s; s++)