From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46159) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gUwjM-0000vK-Gw for qemu-devel@nongnu.org; Thu, 06 Dec 2018 11:42:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gUwjJ-00017E-C6 for qemu-devel@nongnu.org; Thu, 06 Dec 2018 11:42:28 -0500 From: Laurent Vivier References: <20181206151856.77503-1-eblake@redhat.com> Message-ID: <9d93b6c0-43bf-a3fb-ae28-dd4541f5319f@vivier.eu> Date: Thu, 6 Dec 2018 17:42:17 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] cutils: Assert in-range base for string-to-integer conversions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org Cc: qemu-trivial@nongnu.org, vsementsov@virtuozzo.com, armbru@redhat.com Le 06/12/2018 à 17:40, Laurent Vivier a écrit : > Le 06/12/2018 à 16:18, Eric Blake a écrit : >> POSIX states that the value of endptr is unspecified if strtol() >> fails with EINVAL due to an invalid base argument. Since none of >> the callers to check_strtox_error() initialized endptr, we could >> end up propagating uninitialized data back to a caller on error. >> However, passing an out-of-range base is already a sign of poor >> programming, so let's just assert that base is in range, at which >> point check_strtox_error() can be tightened to assert that it is >> receiving an initialized ep that points somewhere within the >> caller's original string, regardless of whether strto*() succeeded >> or failed with ERANGE. >> >> Reported-by: Vladimir Sementsov-Ogievskiy >> Signed-off-by: Eric Blake >> --- >> >> Also tested that this does not negatively impact David's pending >> additions of qemu_strtod{,_finite}(). Thus: >> Based-on: <20181121164421.20780-1-david@redhat.com> >> >> util/cutils.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/util/cutils.c b/util/cutils.c >> index 91930d1bbeb..e098debdc0c 100644 >> --- a/util/cutils.c >> +++ b/util/cutils.c >> @@ -278,6 +278,7 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result) >> static int check_strtox_error(const char *nptr, char *ep, >> const char **endptr, int libc_errno) >> { >> + assert(ep >= nptr); >> if (endptr) { >> *endptr = ep; >> } >> @@ -325,6 +326,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base, >> char *ep; >> long long lresult; >> >> + assert((unsigned) base <= 36 && base != 1); > > If you want to play with type, I think you can do: > > assert((unsigned)(base - 2) <= 34) oops, no, '0' is a valid case. Forgive this... Laurent