amd64/132042: drm module crash the system when closing gnome session

[John Baldwin]

The following reply was made to PR amd64/132042; it has been noted by GNATS.

From: John Baldwin <jhb at freebsd.org>
To: freebsd-amd64 at freebsd.org
Cc: Olivier Cochard-Labbe <olivier at freenas.org>,
        freebsd-gnats-submit at freebsd.org, rnoland at freebsd.org
Subject: Re: amd64/132042: drm module crash the system when closing gnome session
Date: Wed, 25 Feb 2009 09:19:19 -0500

 On Tuesday 24 February 2009 1:40:21 am Olivier Cochard-Labbe wrote:
 > 
 > >Number:         132042
 > >Category:       amd64
 
 This is drm specific and not amd64-specific.
 
 > Fatal trap 12: page fault while in kernel mode
 > cpuid = 0; apic id = 00
 > fault virtual address   = 0x258
 > fault code              = supervisor read data, page not present
 >
 > #7  0xffffffff8050c34e in calltrap () at /usr/src/sys/amd64/amd64/exception.S:209
 > #8  0xffffffff802d47aa in _mtx_lock_sleep (m=0xffffff000348a968, tid=18446742974229954560, opts=Variable "opts" is not available.
 > ) at /usr/src/sys/kern/kern_mutex.c:339
 > #9  0xffffffff802d4b5f in _mtx_lock_flags (m=Variable "m" is not available.
 > ) at /usr/src/sys/kern/kern_mutex.c:186
 > #10 0xffffffffaf18c11d in i915_irq_wait (kdev=Variable "kdev" is not available.
 > ) at /usr/src/sys/modules/drm/i915/../../../dev/drm/i915_irq.c:117
 > #11 0xffffffffaf194179 in drm_ioctl (kdev=0xffffff0001f76400, cmd=2147771461, data=0xffffff002f9d11d0 "\031Y", flags=67,
 >     p=0xffffff0001e8c000) at /usr/src/sys/modules/drm/drm/../../../dev/drm/drm_drv.c:911
 > #12 0xffffffff802ab4d2 in giant_ioctl (dev=0xffffff0001f76400, cmd=2147771461, data=0xffffff002f9d11d0 "\031Y", fflag=67,
 >     td=0xffffff0001e8c000) at /usr/src/sys/kern/kern_conf.c:408
 > 
 > (kgdb) up 10
 > #10 0xffffffffaf18c11d in i915_irq_wait (kdev=Variable "kdev" is not available.
 > ) at /usr/src/sys/modules/drm/i915/../../../dev/drm/i915_irq.c:117
 > 117		DRM_WAIT_ON(ret, dev_priv->irq_queue, 3 * DRM_HZ,
 > 
 > 
 > (kgdb) list *0xffffffff802d47aa
 
 Please go to frame 8 and 'p *m'.  If the 'mtx_lock' member is 6, then the
 mutex is destroyed and it is a use-after-free bug in drm(4).
 
 -- 
 John Baldwin