Hi Dave, just for the record of your trinity scored card - the following bug was found with the help of your tool. -------- Original Message -------- Subject: Re: fuzz tested user mode linux core dumps in fs/lockd/clntproc.c:131 Date: Sun, 28 Jul 2013 19:58:28 +0200 From: Oleg Nesterov <oleg@xxxxxxxxxx> To: Toralf Förster <toralf.foerster@xxxxxx>, Andrey Vagin <avagin@xxxxxxxxxx> CC: Serge E. Hallyn <serue@xxxxxxxxxx>, Eric W. Biederman <ebiederm@xxxxxxxxxxxx>, Al Viro <viro@xxxxxxxxxxxxxxxxxx>, Linux NFS mailing list <linux-nfs@xxxxxxxxxxxxxxx> On 07/28, Toralf Förster wrote: > > The attached patch works - applied on top of current git - > at least the issue cannot be reproduced then. Thanks Toralf. I'll write the changelog and send the patch tomorrow. Andrey, any chance you can check that with this patch free_ipc_ns() doesn't have any problem with ->shm_file ? e7b2c406 should be enough to fix that leak, but it would be nice if you can confirm. > On 07/27/2013 07:00 PM, Oleg Nesterov wrote: > > On 07/27, Toralf Förster wrote: > >> > >> I do have a user mode linux image (stable 32 bit Gentoo Linux ) which erratically crashes > >> while fuzz tested with trinity if the victim files are located on a NFS share. > >> > >> The back trace of the core dumps always looks like the attached. > >> > >> To bisect it is hard. However after few attempts in the last weeks the following > >> commit is either the first bad commit or at least the upper limit (less likely). > >> > >> > >> commit 8aac62706adaaf0fab02c4327761561c8bda9448 > >> Author: Oleg Nesterov <oleg@xxxxxxxxxx> > >> Date: Fri Jun 14 21:09:49 2013 +0200 > >> > >> move exit_task_namespaces() outside of exit_notify() > >> > >> #15 nlmclnt_setlockargs (req=0x48e18860, fl=0x48f27c8c) at fs/lockd/clntproc.c:131 > > > > Thanks. > > > > So nlmclnt_setlockargs()->utsname() crashes and we probably need > > the patch below. > > > > But is it correct? I know _absolutely_ nothing about nfs/sunrpc/etc and > > I never looked into this code before, most probably I am wrong. > > > > But it seems that __nlm_async_call() relies on workqueues. > > nlmclnt_async_call() does rpc_wait_for_completion_task(), but what if > > the caller is killed? > > > > nlm_rqst can't go away, ->a_count was incremented. But can't the caller > > exit before call->name is used? In this case the memory it points to > > can be already freed. > > > > Oleg. > > > > --- x/kernel/exit.c > > +++ x/kernel/exit.c > > @@ -783,8 +783,8 @@ void do_exit(long code) > > exit_shm(tsk); > > exit_files(tsk); > > exit_fs(tsk); > > - exit_task_namespaces(tsk); > > exit_task_work(tsk); > > + exit_task_namespaces(tsk); > > check_stack_usage(); > > exit_thread(); > > > > > > > > > -- > MfG/Sincerely > Toralf Förster > pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3 -- To unsubscribe from this list: send the line "unsubscribe trinity" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
