On 01/24/2012 03:47 PM, Daniel Vetter wrote:
On Tue, Jan 24, 2012 at 10:31:46AM +0100, Thomas Hellstrom wrote:
If the master tries to authenticate a client using drm_authmagic and
that client has already closed its drm file descriptor,
either wilfully or because it was terminated, the
call to drm_authmagic will dereference a stale pointer into kmalloc'ed memory
and corrupt it.
Typically this results in a hard system hang.
This patch fixes that problem by removing any authentication tokens
(struct drm_magic_entry) open for a file descriptor when that file
descriptor is closed.
Signed-off-by: Thomas Hellstrom<thellstrom@xxxxxxxxxx>
Ok, I've wandered around a bit in this and noticed that the locking is the
usual convoluted disaster. We seem to randomly grab dev->struct_mutex in
the auth and master ioctl, but all the real protect seems to be due to
taking the global mutex in all relevant paths.
I guess I can't volunteer you to clean this up ;-)
It would be pretty easy to make thos ioctls unlocked (we should probably
also have an idr managing the magic number)
but my wife is having twins in a couple of weeks and
I've got a long list of bugs to fix before that for the vmwgfx launch so I
unfortunately have to pass this time.
/Thomas
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