From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35949) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a1bpZ-0005ED-3w for qemu-devel@nongnu.org; Wed, 25 Nov 2015 10:18:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a1bpU-00064g-Rd for qemu-devel@nongnu.org; Wed, 25 Nov 2015 10:18:01 -0500 References: <1448407631-9405-1-git-send-email-jsnow@redhat.com> <871tbeijay.fsf@blackfin.pond.sub.org> From: John Snow Message-ID: <5655D122.8010601@redhat.com> Date: Wed, 25 Nov 2015 10:17:54 -0500 MIME-Version: 1.0 In-Reply-To: <871tbeijay.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [trivial for-2.6] util/id: fully allocate names table List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: qemu-trivial@nongnu.org, jcody@redhat.com, qemu-devel@nongnu.org On 11/25/2015 03:18 AM, Markus Armbruster wrote: > John Snow writes: > >> Trivial: this array should be allocated to have ID_MAX entries always. >> Otherwise if someone were to forget to expand this table, the assertion >> in the id generator won't actually trigger; it will read junk data. > > You mean this one: > > assert(id < ID_MAX); > Well, sort of. I meant 'assert(id_subsys_str[id])' itself. If you forget to expand the list (It happened to a friend of mine) this assert will pass because it reads garbage. If you just always expand the full table, though, it will catch you (Err, my friend) being a dummy a little more nicely. My thought is we need both the range and presence checks. I'll v2 it, thanks. --js > The assertion is crap, because it fails to protect array access > id_subsys_str[id]. Here's one that does: > > assert(0 <= id && id < ARRAY_SIZE(id_subsys_str)); > >> Signed-off-by: John Snow >> --- >> util/id.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/util/id.c b/util/id.c >> index bcc64d8..b7ca4d2 100644 >> --- a/util/id.c >> +++ b/util/id.c >> @@ -29,7 +29,7 @@ bool id_wellformed(const char *id) >> >> #define ID_SPECIAL_CHAR '#' >> >> -static const char *const id_subsys_str[] = { >> +static const char *const id_subsys_str[ID_MAX] = { >> [ID_QDEV] = "qdev", >> [ID_BLOCK] = "block", >> };