Messages in this thread | | | Subject | Re: DoS with POSIX file locks? | From | Trond Myklebust <> | Date | Tue, 21 Mar 2006 13:16:41 -0500 |
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On Tue, 2006-03-21 at 18:58 +0100, Miklos Szeredi wrote: > > > Apps using LinuxThreads seem to be candidates: > > > > > > According to POSIX 1003.1c, a successful `exec*' in one of the > > > threads should automatically terminate all other threads in the > > > program. This behavior is not yet implemented in LinuxThreads. > > > Calling `pthread_kill_other_threads_np' before `exec*' achieves > > > much of the same behavior, except that if `exec*' ultimately > > > fails, then all other threads are already killed. > > > > > > steal_locks() was probably added as a workaround for this case, no? > > > > Possibly, but LinuxThreads were never really POSIX thread compliant > > anyway. Anyhow, the problem isn't really LinuxThreads, it is rather that > > the existence of the standalone CLONE_FILES flag allows you to do a lot > > of weird inheritance crap with 'posix locks' that the POSIX standards > > committees never even had to consider. > > Yes. The execve-with-multiple-threads/posix-locks interaction is not > documented for LinuxThreads but removing steal_locks() makes that > implementation slighly differently incompatible to POSIX. Some > application _might_ be relying on the current behavior.
That really doesn't matter: the current behaviour isn't ever going to work for some of the most commonly used Linux filesystems out there. IOW: Such an application isn't even going to be portable from one Linux installation to another.
Cheers, Trond
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