linux-kernel - Re: [BUG] signal: multithread program returns with wrong errno on receiving SIGSTOP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87646caw5a.wl%takeuchi_satoru@jp.fujitsu.com>
Date:	Tue, 29 May 2007 17:09:37 +0900
From:	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Oleg Nesterov <oleg@...sign.ru>,
	Roland McGrath <roland@...hat.com>
Subject: Re: [BUG] signal: multithread program returns with wrong errno on receiving SIGSTOP

Hi Andrew,

> What kernel versions is this occurring on?

2.6.22-rc3 is.

Satoru

At Tue, 29 May 2007 01:03:15 -0700,
Andrew Morton wrote:
> 
> On Mon, 28 May 2007 11:32:00 +0900 Satoru Takeuchi <takeuchi_satoru@...fujitsu.com> wrote:
> 
> > Hi,
> > 
> > I found a bug on signal subsystem. If there is some multithread program
> > and one of the thread is blocking on the system call, it returns with
> > wrong errno on receiving SIGSTOP and following SIGCONT.
> > 
> > Arch dependency
> > ===============
> > 
> > succeed to reproduce: i386, ia64
> > Unknown:              any other arch
> > 
> > # I suspect that this problem occur on any arch...
> > 
> > How to reproduce
> > ================
> > 
> > This process needs 2 terminals, term A and term B.
> > 
> > 1. issue the test program (attached on this mail) from term A.
> > 
> >    $ ./mt-wrong-errno
> > 
> > 2. send SIGSTOP to test program from term B.
> > 
> >    $ ps a
> >    ...
> >     9685 pts/3    Sl+    0:00 ./mt-wrong-errno
> >     9688 pts/4    R+     0:00 ps a
> >    $ kill -STOP 9685
> > 
> > 3. send SIGCONT to test program from term B.
> > 
> >    $ kill -CONT 9685
> > 
> > Expected Result
> > ===============
> > 
> > `./mt-wrong-errno' restarts read syscall (and stop again by receiving
> > SIGTTIN).
> > 
> > Actual Result
> > =============
> > 
> > `./mt-wrong-errno' returns with wrong errno 512 means ERESTARTSYS.
> > The comment on include/linux/errno.h says "this errno should never be
> > seen by user program." So it's definitely a bug.
> > 
> >   output of term A
> >   ----------------
> > 
> >     $ ./mt-wrong-errno
> > 
> >     [1]+  Stopped                 ./mt-wrong-errno
> >     $ errno = 512
> > 
> >   output of term B
> >   ----------------
> > 
> >     $ ps a
> >     ...
> >      9685 pts/3    Sl+    0:00 ./mt-wrong-errno
> >      9688 pts/4    R+     0:00 ps a
> >     $ kill -STOP 9685
> >     $ kill -CONT 9685
> > 
> > 
> > This problem can always reproduce, so it's no timing issue. I suspect
> > that group_stop_count counting mechanism has something wrong and
> > signal handling is canceled erroneously. 
> > 
> > Any hints or patch itself are welcome.
> > 
> > Thanks,
> > 
> > Satoru
> > 
> > -------------------------------------------------------------------------------
> > /*
> >  * mt-wrong-errno.c
> >  * 
> >  * Copyright 2007 Satoru Takeuchi <takeuchi_satoru@...futjisu.com>
> >  *
> >  * This software may be used and distributed according to the terms
> >  * of the GNU General Public License, incorporated herein by reference.
> >  * 
> >  */
> > 
> > #include <sys/types.h>
> > #include <pthread.h>
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <err.h>
> > #include <unistd.h>
> > #include <stdio.h>
> > #include <errno.h>
> > 
> > void *thread_fn(void *arg)
> > {
> > 	char c;
> > 	int ret;
> > 
> > 	ret = read(STDIN_FILENO, &c, 1);
> > 	if (ret < 0)
> > 		printf("errno = %d\n", errno);
> > 
> > 	return NULL;
> > }
> > 
> > int main(int argc, char *argv[])
> > {
> > 	pthread_t t;
> > 	
> > 	if (pthread_create(&t, NULL, thread_fn, NULL))
> > 		err(EXIT_FAILURE, "pthread_create() failed\n");
> > 	
> > 	if (pthread_join(t, NULL))
> > 		warn("pthread_join() failed\n");
> > }
> 
> What kernel versions is this occurring on?
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/