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 77B3E385E44A; Mon,  9 Aug 2021 12:14:01 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 77B3E385E44A
From: "npv1310 at gmail dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug librt/28213] New: NULL pointer dereference due to
 CVE-2021-33574 fix
Date: Mon, 09 Aug 2021 12:14:00 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: glibc
X-Bugzilla-Component: librt
X-Bugzilla-Version: unspecified
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: npv1310 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 target_milestone
Message-ID: <bug-28213-131@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
X-BeenThere: glibc-bugs@sourceware.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Glibc-bugs mailing list <glibc-bugs.sourceware.org>
List-Unsubscribe: <https://sourceware.org/mailman/options/glibc-bugs>,
 <mailto:glibc-bugs-request@sourceware.org?subject=unsubscribe>
List-Archive: <https://sourceware.org/pipermail/glibc-bugs/>
List-Help: <mailto:glibc-bugs-request@sourceware.org?subject=help>
List-Subscribe: <https://sourceware.org/mailman/listinfo/glibc-bugs>,
 <mailto:glibc-bugs-request@sourceware.org?subject=subscribe>
X-List-Received-Date: Mon, 09 Aug 2021 12:14:01 -0000

https://sourceware.org/bugzilla/show_bug.cgi?id=3D28213

            Bug ID: 28213
           Summary: NULL pointer dereference due to CVE-2021-33574 fix
           Product: glibc
           Version: unspecified
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: librt
          Assignee: unassigned at sourceware dot org
          Reporter: npv1310 at gmail dot com
  Target Milestone: ---

Hello.
While investigating the upstream fix of the recent CVE-2021-33574, i've fou=
nd
following problem:
Helper thread frees copied attribute on NOTIFY_REMOVED message received from
the OS kernel. Unfortunately, it fails to check whether copied attribute
actually exists (data.attr !=3D NULL). This worked earlier because free() c=
hecks
passed pointer before actually attempting to release corresponding memory. =
But
__pthread_attr_destroy assumes pointer is not NULL. So passing NULL pointer=
 to
__pthread_attr_destroy will result in segmentation fault. This scenario is
possible if notification->sigev_notify_attributes =3D=3D NULL (which means =
default
thread attributes should be used).
Affected file: sysdeps/unix/sysv/linux/mq_notify.c
Affected function: helper_thread
Affected lineno: 137

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