Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Sat, 18 Nov 2017 20:14:33 -0500
From: Rich Felker <dalias@...c.org>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] fix fgetwc when decoding a character that crosses
 buffer boundary

On Sat, Nov 18, 2017 at 08:12:57PM -0500, Rich Felker wrote:
> On Sat, Nov 18, 2017 at 05:51:48PM +0100, Szabolcs Nagy wrote:
> > Update the buffer position according to the bytes consumed into st when
> > decoding an incomplete character at the end of the buffer.
> > ---
> >  src/stdio/fgetwc.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/src/stdio/fgetwc.c b/src/stdio/fgetwc.c
> > index e455cfec..a00c1a86 100644
> > --- a/src/stdio/fgetwc.c
> > +++ b/src/stdio/fgetwc.c
> > @@ -15,20 +15,21 @@ static wint_t __fgetwc_unlocked_internal(FILE *f)
> >  	if (f->rpos < f->rend) {
> >  		l = mbrtowc(&wc, (void *)f->rpos, f->rend - f->rpos, &st);
> >  		if (l+2 >= 2) {
> >  			f->rpos += l + !l; /* l==0 means 1 byte, null */
> >  			return wc;
> >  		}
> >  		if (l == -1) {
> >  			f->rpos++;
> >  			return WEOF;
> >  		}
> > +		f->rpos = f->rend;
> >  	} else l = -2;
> 
> Thanks, applying! Here is a test case that demonstrates the bug
> reproducibly; feel free to adapt (it should probably use the framework
> functions for getting a utf-8 locale and error reporting) & include it
> in libc-test.
> 
> Rich

> #include <stdio.h>
> #include <poll.h>
           ^^^^^^^^

Ooops, this is spurious/leftover from when I thought I was going to
need to do something fancier to reliably trigger it.

> #include <locale.h>
> #include <wchar.h>
> #include <unistd.h>
> 
> int main()
> {
> 	setlocale(LC_CTYPE, "");
> 	int p[2];
> 	pipe(p);
> 	write(p[1], "x\340\240", 3);
> 	dup2(p[0], 0);
> 	wchar_t wc;
> 	wc = fgetwc(stdin);
> 	write(p[1], "\200", 1);
> 	close(p[1]);
> 	wc = fgetwc(stdin);
> 	printf("got %x\n", wc);
> }

Powered by blists - more mailing lists

Your e-mail address:

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.