From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <sourceware-bugzilla@sourceware.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 06AC638582BC; Tue,  8 Aug 2023 15:52:49 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 06AC638582BC
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org;
	s=default; t=1691509969;
	bh=0ioA5BxvNO3kLIpICf5/QzC63rhk5z/dod2fzNUsYx8=;
	h=From:To:Subject:Date:From;
	b=OEzsAmr2VVszh0NAyyIbCTWSTi+rhZdluWRvJMb5kDcmV0G/RwMJPu6Fsfqbumc76
	 m+FKZBTwwdA0s3+zrjapEhXZywOOZaZFiYquPLAL4eh5cTHJqq7W2JoT+pRrjgohSw
	 FEzrpFe66HCAvpjo6auXbBNoYyG3A/UL5HEBg588=
From: "markgaleck at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug libc/30737] New: fdopendir() is not robust - returns bogus DIR*
 instead of flagging an error
Date: Tue, 08 Aug 2023 15:52:48 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: glibc
X-Bugzilla-Component: libc
X-Bugzilla-Version: 2.35
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: markgaleck at gmail dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at sourceware dot org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter cc target_milestone
Message-ID: <bug-30737-131@http.sourceware.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://sourceware.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <glibc-bugs.sourceware.org>

https://sourceware.org/bugzilla/show_bug.cgi?id=3D30737

            Bug ID: 30737
           Summary: fdopendir() is not robust - returns bogus DIR* instead
                    of flagging an error
           Product: glibc
           Version: 2.35
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: markgaleck at gmail dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

First, dislclaimer: I checked this issue is present on the latest Ubuntu
distribution, which has glibc version 2.35, not the latest stable 2.38.  I =
was
able to build 2.38 locally, but I am not able to force Ubuntu to accept it =
for
linking to the sample program, or to upgrade the installed glibc 2.35 to 2.=
38.=20

If you know how to test the sample program with 2.38, please let me know, a=
nd I
will do so and I will remove this report if it does not reproduce with glibc
2.38.
---------------------------

Here is the SSCCE=20
'foobar.c'

(which I obtained by necessary modifications to the sample code in man7 ent=
ry
for fdopendir() ) :


#define _GNU_SOURCE

#include <stdio.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>

int
main(int argc, char* argv[])
{
    DIR* d;
    struct dirent* dp;
    int dfd;

    if ((d =3D fdopendir(open("./dir", O_RDONLY | O_PATH | O_DIRECTORY))) =
=3D=3D
NULL) {
        fprintf(stderr, "Cannot open directory\n");
        exit(1);
    }

    while ((dp =3D readdir(d)) !=3D NULL) {
        if (!strcmp(dp->d_name, "."))
            continue;
        if (!strcmp(dp->d_name, ".."))
            continue;
        printf("d_name %s\n", dp->d_name);
    }
    return 0;
}

-------------------------
Here is a script to show the problem:

$ mkdir dir
$ touch dir/file
$ gcc -lc foobar.c
$ ./a.out
$

When called on a descriptor opened with O_PATH , fdopendir() succeeds happi=
ly,
but then, readdir() reports nothing!

So the DIR* returned from fdopendir() is useless, but fdopendir() returns i=
t,
instead of NULL and setting errno to EBADF , as it should INHO


If I remove | O_PATH from the above sample code, I get the expected result:

$gcc -lc foobar.c
$ ./a.out
d_name file

--=20
You are receiving this mail because:
You are on the CC list for the bug.=