Date: Wed, 5 Jan 2011 17:55:45 +0100 From: Ulrich =?utf-8?B?U3DDtnJsZWlu?= <uqs@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-current@freebsd.org, Erik Cederstrand <erik@cederstrand.dk> Subject: Re: FYI: clang static analyzer page has moved to http://scan.freebsd.your.org/freebsd-head/ Message-ID: <20110105165545.GP23329@acme.spoerlein.net> In-Reply-To: <201101050934.49845.jhb@freebsd.org> References: <20110105131439.GN23329@acme.spoerlein.net> <4184C8F2-3C6D-46FB-8F10-DDEBA6DB1C35@cederstrand.dk> <AD2AEFFB-37A4-4DAB-9094-7289C1C8B0DD@cederstrand.dk> <201101050934.49845.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, 05.01.2011 at 09:34:49 -0500, John Baldwin wrote: > On Wednesday, January 05, 2011 9:11:50 am Erik Cederstrand wrote: > > > > Den 05/01/2011 kl. 14.56 skrev Erik Cederstrand: > > > > > Ignoring contrib code for the moment, I decided to look at usr.sbin.pw > > > from 2011-01-05. There's one report (http://scan.freebsd.your.org/freebsd-head/usr.sbin.pw/2011-01-05-amd64/report-KkilQ3.html#EndPath) > > > which turns out to be a false positive: > > > > > > * Step 6 calls cmdhelp() on line 168; > > > * cmdhelp() ends with "exit(EXIT_FAILURE);" on line 432 which I assume > > > is exit(3) from libc > > > * The analyzer doesn't know that this function never returns and > > > continues to flag a null dereference in step 8 > > > > The same is true of err(), verr(), errc(), verrc(), errx(), and verrx() > > which is also causing false positive reports. They ultimately call exit(3). > > These are all marked as __dead2, so the compiler should "know" that these do > not return. And clang did the right thing here in the past. Beware that it does no inter-procedural analysis yet, so it will usually miss that usage() calls exit unconditionally. *But*, it should grok that for err(3) and exit(3). Now there are some possible remedies: - get IPA to work with clang, or at least file a bug - mark functions as __dead2 (please don't do that) - come up with a way to mark the false positives (kinda impossible with the way scan-build currently works) All interested parties with src access are encouraged to take a look at our Coverity Prevent installation (which is down for maintenance, but should be up soon). Regards, Uli
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110105165545.GP23329>