From: Roberto Sassu <roberto.sassu@huawei.com> stable inclusion from stable-5.10.75 commit faba7916cdc0da11c7402538fe95642b43c7b73b bugzilla: 182987 https://gitee.com/openeuler/kernel/issues/I4I3MP Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 8e0ab8e26b72a80e991c66a8abc16e6c856abe3d upstream. Fix two problems found in the strrchr() implementation for s390 architectures: evaluate empty strings (return the string address instead of NULL, if '\0' is passed as second argument); evaluate the first character of non-empty strings (the current implementation stops at the second). Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: Heiko Carstens <hca@linux.ibm.com> (incorrect behavior with empty strings) Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Link: https://lore.kernel.org/r/20211005120836.60630-1-roberto.sassu@huawei.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- arch/s390/lib/string.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/arch/s390/lib/string.c b/arch/s390/lib/string.c index 93b3209b94a2..db4e539d8c7f 100644 --- a/arch/s390/lib/string.c +++ b/arch/s390/lib/string.c @@ -246,14 +246,13 @@ EXPORT_SYMBOL(strcmp); #ifdef __HAVE_ARCH_STRRCHR char *strrchr(const char *s, int c) { - size_t len = __strend(s) - s; - - if (len) - do { - if (s[len] == (char) c) - return (char *) s + len; - } while (--len > 0); - return NULL; + ssize_t len = __strend(s) - s; + + do { + if (s[len] == (char)c) + return (char *)s + len; + } while (--len >= 0); + return NULL; } EXPORT_SYMBOL(strrchr); #endif -- 2.20.1