From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/10033 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: nftw miscalculates FTW.base when pathnames end in / Date: Fri, 13 May 2016 23:01:09 -0400 Message-ID: <20160514030109.GN21636@brightrain.aerifal.cx> References: <1462369339.29574.1@mail.zhasha.com> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1463194889 7495 80.91.229.3 (14 May 2016 03:01:29 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 14 May 2016 03:01:29 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-10046-gllmg-musl=m.gmane.org@lists.openwall.com Sat May 14 05:01:28 2016 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1b1PpX-0002Z3-Nl for gllmg-musl@m.gmane.org; Sat, 14 May 2016 05:01:27 +0200 Original-Received: (qmail 7692 invoked by uid 550); 14 May 2016 03:01:23 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 7673 invoked from network); 14 May 2016 03:01:22 -0000 Content-Disposition: inline In-Reply-To: <1462369339.29574.1@mail.zhasha.com> User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:10033 Archived-At: On Wed, May 04, 2016 at 03:42:19PM +0200, Joakim Sindholt wrote: > Running the test program from the glibc ftw man page[1]: > > +zhasha@wirbelwind /home/zhasha ; ./6.out test > d 0 4096 test 0 test > d 1 4096 test/a 5 a > f 2 0 test/a/1 7 1 > d 1 4096 test/b 5 b > f 2 0 test/b/1 7 1 > f 2 0 test/b/2 7 2 > d 1 4096 test/ddd 5 ddd > f 2 0 test/ddd/5 9 5 > d 1 4096 test/cc 5 cc > f 2 0 test/cc/3 8 3 > +zhasha@wirbelwind /home/zhasha ; ./6.out test/ > d 0 4096 test/ 4 / > d 1 4096 test/a 6 > f 2 0 test/a/1 7 1 > d 1 4096 test/b 6 > f 2 0 test/b/1 7 1 > f 2 0 test/b/2 7 2 > d 1 4096 test/ddd 6 dd > f 2 0 test/ddd/5 9 5 > d 1 4096 test/cc 6 c > f 2 0 test/cc/3 8 3 > > The final 2 columns are the file name length and path + ftw->base > respectively, which is off by one when the path ends in /. It also > seems to confuse the initial dir name. > > I have attached a fix but I'm not sure it's a particularly good one. > > [1] http://linux.die.net/man/3/ftw > diff --git a/src/misc/nftw.c b/src/misc/nftw.c > index efb2b89..7c2c0d3 100644 > --- a/src/misc/nftw.c > +++ b/src/misc/nftw.c > @@ -108,11 +108,13 @@ int nftw(const char *path, int (*fn)(const char *, const struct stat *, int, str > if (fd_limit <= 0) return 0; > > l = strlen(path); > + while (l && path[l-1]=='/') --l; > if (l > PATH_MAX) { > errno = ENAMETOOLONG; > return -1; > } > - memcpy(pathbuf, path, l+1); > + memcpy(pathbuf, path, l); > + pathbuf[l]='\0'; > > pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs); > r = do_nftw(pathbuf, fn, fd_limit, flags, NULL); Thanks for reminding me to look at this today. I've actually read the code, and while your patch should avoid the problem, I agree it's probably not the right fix (interpreting and alterring the part of the path passed by the application). Instead, I think the error is in the computations of new.base and lev.base. new.base should be equal to the offset at which de->d_name is pasted into the buffer, which is j+1, not l+1; these only differ when path ends in a slash. lev.base is computed separately depending on whether or not there's a previous history; for the no-history case, it should be computed by skipping all trailing slashes, then backing up until the previous slash or beginning of string, whichever is hit first. But rather than special-casing !h in do_nftw, the top-level nftw function should probably set up a fake "-1 level" history structure to pass in. This gathers the special top-level logic all in one place. Can you try these ideas and see if they work for you? If not I'll give them a try soon, but I've got a few other things I need to do first. Rich