Date: Wed, 20 Oct 2004 12:03:10 GMT From: Andriy Gapon <avg@icyb.net.ua> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/72922: linux emulation: suid/sgid threaded applications hang Message-ID: <200410201203.i9KC3Aff096506@www.freebsd.org> Resent-Message-ID: <200410201210.i9KCAVti045860@freefall.freebsd.org>
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>Number: 72922 >Category: kern >Synopsis: linux emulation: suid/sgid threaded applications hang >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Oct 20 12:10:31 GMT 2004 >Closed-Date: >Last-Modified: >Originator: Andriy Gapon >Release: 5.2.1-RELEASE-p11 >Organization: >Environment: 5.2.1-RELEASE-p11 i386 linux_base-7.1_7 linux_devtools-7.1_3 >Description: linux applications using old linux threads (pre-NPTL) use signal 32 (linux SIGRTMIN) for communication between thread-processes. If such an linux application is installed suid or sgid and security.bsd.conservative_signals=1 (default), then permission will be denied to send such a signal and the application will freeze. Please see http://docs.freebsd.org/cgi/getmsg.cgi?fetch=13492+0+archive/2004/freebsd-emulation/20041017.freebsd-emulation for an example and detailed investigation of such case. >How-To-Repeat: using the same environment as mine 1. make any threaded linux application suid 2. run it so that it really changes privileges 3. see it freeze >Fix: 1. either add signal 32 (linux SIGRTMIN) to list of "common signals" in cr_cansignal() 2. or detect the described situation in cr_cansignal() and produce a warning message explaining the situation and suggesting setting security.bsd.conservative_signals=0 >Release-Note: >Audit-Trail: >Unformatted:
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