linux-kernel - Re: fanotify bug on gdb -- hard crash

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Date:	Tue, 30 Dec 2014 19:21:49 -0500
From:	Eric Paris <eparis@...hat.com>
To:	ivo welch <ivo.welch@...il.com>
Cc:	Heinrich Schuchardt <xypron.glpk@....de>,
	linux-kernel@...r.kernel.org
Subject: Re: fanotify bug on gdb -- hard crash

On Mon, 2014-12-29 at 13:06 +0800, ivo welch wrote:
> thank you, eric.  will do.  I read up on it above and now understand it better.

Great let us know if it keeps giving you trouble!

> the example in the man page seems somewhat misfortunate.  I would use
> an example that does not, by default, lock up the user system.
> (perhaps add a second example with the _PERM feature that shows how it
> responds.)

The link you gave does respond and allow permissions:

               if (metadata->fd >= 0) {

                       /* Handle open permission event */

                       if (metadata->mask & FAN_OPEN_PERM) {
                           printf("FAN_OPEN_PERM: ");

                           /* Allow file to be opened */

                           response.fd = metadata->fd;
                           response.response = FAN_ALLOW;
                           write(fd, &response,
                                 sizeof(struct fanotify_response));
                       }

That's the key bit of the example...  If you use gdb and never get to
there, you are in a bit of trouble, I agree!

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