From: Al Viro <[email protected]>
To: Matthew Wilcox <[email protected]>
Cc: Jens Axboe <[email protected]>,
Pavel Begunkov <[email protected]>,
[email protected], [email protected],
Linus Torvalds <[email protected]>
Subject: Re: [PATCH 3/3] io_uring: refactor io_sq_offload_create()
Date: Sat, 24 Jul 2021 01:31:54 +0000 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On Sat, Jul 24, 2021 at 12:45:12AM +0100, Matthew Wilcox wrote:
> On Fri, Jul 23, 2021 at 08:19:49PM +0000, Al Viro wrote:
> > To elaborate: ->release() instance may not assume anything about current->mm,
> > or assume anything about current, for that matter. It is entirely possible
> > to arrange its execution in context of a process that is not yours and had not
> > consent to doing that. In particular, it's a hard bug to have _any_ visible
> > effects depending upon the memory mappings, memory contents or the contents of
> > descriptor table of the process in question.
>
> Hmm. Could we add a poison_current() function? Something like ...
>
> static inline void call_release(struct file *file, struct inode *inode)
> {
> void *tmp = poison_current();
> if (file->f_op->release)
> file->f_op->release(inode, file);
> restore_current(tmp);
> }
>
> Should be straightforward for asm-generic/current.h and for x86 too.
> Probably have to disable preemption? Maybe interrupts too? Not sure
> what's kept in current these days that an interrupt handler might
> rely on being able to access temporarily.
->release() might grab a mutex, for example. Scheduler is going to be unhappy
if it runs into somebody playing silly buggers with current...
next prev parent reply other threads:[~2021-07-24 1:38 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-20 11:03 [PATCH 0/3] small 5.13 cleanups Pavel Begunkov
2021-04-20 11:03 ` [PATCH 1/3] io_uring: move inflight un-tracking into cleanup Pavel Begunkov
2021-04-20 11:03 ` [PATCH 2/3] io_uring: safer sq_creds putting Pavel Begunkov
2021-04-20 11:03 ` [PATCH 3/3] io_uring: refactor io_sq_offload_create() Pavel Begunkov
2021-07-22 21:59 ` Al Viro
2021-07-22 23:06 ` Jens Axboe
2021-07-22 23:30 ` Al Viro
2021-07-22 23:42 ` Jens Axboe
2021-07-23 0:10 ` Al Viro
2021-07-23 0:12 ` Al Viro
2021-07-23 16:17 ` Jens Axboe
2021-07-23 17:11 ` Al Viro
2021-07-23 17:32 ` Jens Axboe
2021-07-23 17:36 ` Jens Axboe
2021-07-23 17:56 ` Jens Axboe
2021-07-23 19:00 ` Al Viro
2021-07-23 20:10 ` Jens Axboe
2021-07-23 20:24 ` Al Viro
2021-07-23 22:32 ` Jens Axboe
2021-07-23 20:19 ` Al Viro
2021-07-23 23:45 ` Matthew Wilcox
2021-07-23 23:57 ` Jens Axboe
2021-07-24 1:31 ` Al Viro [this message]
2021-07-23 0:03 ` Al Viro
2021-07-23 9:59 ` Pavel Begunkov
2021-04-20 18:55 ` [PATCH 0/3] small 5.13 cleanups Jens Axboe
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