Messages in this thread Patch in this message | | | Date | Fri, 30 Jul 2004 01:56:54 +0200 | From | Roger Luethi <> | Subject | Re: Interesting race condition... |
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On Thu, 22 Jul 2004 22:04:46 -0500, Rob Landley wrote: > I just saw a funky thing. Here's the cut and past from the xterm... > > [root@(none) root]# ps ax | grep hack > 9964 pts/1 R 0:00 grep hack HOSTNAME= SHELL=/bin/bash TERM=xterm HISTSIZE=1000 USER=root LS_COLORS=no=00:fi=00:di=00;34:ln=00;36:pi=40;33:so=00;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=00;32:*.cmd=00;32:*.exe=00;32:*.com=00;32:*.btm=00;32:*.bat=00;32:*.sh=00;32:*.csh=00;32:*.tar=00;31:*.tgz= > [root@(none) root]# ps ax | grep hack > 9966 pts/1 S 0:00 grep hack > > Seems like some kind of race condition, dunno if it's in Fedore Core 1's ps > or the 2.6.7 kernel or what...
If somebody posted a solution for this, I didn't see it. There's a race in the kernel, and considering the permissions on /proc/PID/{cmdline,environ} a security bug as well: If you win the race with a starting process, you can read its environment.
This should plug the hole. Can you give it a spin?
Roger
--- linux-2.6.8-rc2-bk1/fs/proc/base.c.orig 2004-07-30 01:43:23.535967505 +0200 +++ linux-2.6.8-rc2-bk1/fs/proc/base.c 2004-07-30 01:43:27.428303752 +0200 @@ -329,6 +329,8 @@ static int proc_pid_cmdline(struct task_ struct mm_struct *mm = get_task_mm(task); if (!mm) goto out; + if (!mm->arg_end) + goto out; /* Shh! No looking before we're done */ len = mm->arg_end - mm->arg_start; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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