From 592b5fcb984487f1929d28e1f4eb49d25c2c719d Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 13 Mar 2019 11:23:28 +0100 Subject: [PATCH] string: avoid undefined behavior in strrchr() The pre-decrement would not only cause misbehavior when wrapping (benign because there shouldn't be any NULL pointers passed in), but may also create a pointer pointing outside the object that the passed in pointer points to (it won't be de-referenced though). Take the opportunity and also - convert bogus space (partly 7 of them) indentation to Linux style tab one, - add two blank lines. Signed-off-by: Jan Beulich Reviewed-by: Juergen Gross Acked-by: Andrew Cooper --- xen/common/string.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/xen/common/string.c b/xen/common/string.c index 1e122abca8..b8639dd30d 100644 --- a/xen/common/string.c +++ b/xen/common/string.c @@ -174,12 +174,13 @@ char *(strchr)(const char *s, int c) */ char *(strrchr)(const char *s, int c) { - const char *p = s + strlen(s); - do { - if (*p == (char)c) - return (char *)p; - } while (--p >= s); - return NULL; + const char *p = s + strlen(s); + + for (; *p != (char)c; --p) + if (p == s) + return NULL; + + return (char *)p; } #endif -- 2.30.2