Date: Wed, 18 Sep 2002 19:23:31 -0700 (PDT) From: pqf <pqf@163.net> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/42943: fd 0,1,2 should not be set to nonblock in _thread_fd_table_init() Message-ID: <200209190223.g8J2NVDO061737@www.freebsd.org>
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>Number: 42943
>Category: misc
>Synopsis: fd 0,1,2 should not be set to nonblock in _thread_fd_table_init()
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Wed Sep 18 19:30:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: pqf
>Release: FreeBSD bsd 4.6.2-RELEASE
>Organization:
www.tebie.com
>Environment:
FreeBSD bsd 4.6.2-RELEASE FreeBSD 4.6.2-RELEASE #0: Wed Aug 14 21:23:26 GMT 2002 murray@builder.freebsdmall.com:/usr/src/sys/compile/GENERIC i386
>Description:
in uthread_fd.c line 141, it set fd 0, 1, 2 to nonblock mode, and so the fd 0, 1, 2 in kernel is nonblock mode, but the mode of them in uthread level MAY be blocking
normally, it's ok to do so, but think about the following condition:
parend process call dup2() to make fd 0 be a unix domain socket
parent process fork() muti-thread(pthread) child process
child process set fd 0 to nonblock in _thread_fd_table_init()
fd 0 is shared between parent process and child process, so the parent process's fd 0 is now nonblock, but the parent process DO NOT know what happen because it DID NOT do anything to fd 0...
>How-To-Repeat:
>Fix:
comment line 140 to line 143 in uthread_fd.c
>Release-Note:
>Audit-Trail:
>Unformatted:
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