[Intel-gfx] [PATCH] drm/i915: Fix use after free in lpe_audio_platdev_destroy()
Chris Wilson
chris at chris-wilson.co.uk
Tue Apr 11 21:20:56 UTC 2017
On Tue, Apr 11, 2017 at 11:01:57PM +0200, Takashi Iwai wrote:
> On Tue, 11 Apr 2017 22:41:12 +0200,
> Chris Wilson wrote:
> >
> > On Wed, Mar 01, 2017 at 06:59:18PM +0000, Chris Wilson wrote:
> > > [31908.547136] BUG: KASAN: use-after-free in intel_lpe_audio_teardown+0x78/0xb0 [i915] at addr ffff8801f7788358
> > > [31908.547297] Read of size 8 by task drv_selftest/3781
> > > [31908.547405] CPU: 0 PID: 3781 Comm: drv_selftest Tainted: G BU W 4.10.0+ #451
> > > [31908.547553] Hardware name: / , BIOS PYBSWCEL.86A.0027.2015.0507.1758 05/07/2015
> > > [31908.547682] Call Trace:
> > > [31908.547772] dump_stack+0x68/0x9f
> > > [31908.547857] kasan_object_err+0x1c/0x70
> > > [31908.547947] kasan_report_error+0x1f1/0x4f0
> > > [31908.548038] ? kfree+0xaa/0x170
> > > [31908.548121] kasan_report+0x34/0x40
> > > [31908.548211] ? klist_children_get+0x20/0x30
> > > [31908.548472] ? intel_lpe_audio_teardown+0x78/0xb0 [i915]
> > > [31908.548567] __asan_load8+0x5e/0x70
> > > [31908.548824] intel_lpe_audio_teardown+0x78/0xb0 [i915]
> > > [31908.549080] intel_audio_deinit+0x28/0x80 [i915]
> > > [31908.549315] i915_driver_unload+0xe4/0x360 [i915]
> > > [31908.549551] ? i915_driver_load+0x1d70/0x1d70 [i915]
> > > [31908.549651] ? trace_hardirqs_on+0xd/0x10
> > > [31908.549885] i915_pci_remove+0x23/0x30 [i915]
> > > [31908.549978] pci_device_remove+0x5c/0x100
> > > [31908.550069] device_release_driver_internal+0x1db/0x2e0
> > > [31908.550165] driver_detach+0x68/0xc0
> > > [31908.550256] bus_remove_driver+0x8b/0x150
> > > [31908.550346] driver_unregister+0x3e/0x60
> > > [31908.550439] pci_unregister_driver+0x1d/0x110
> > > [31908.550531] ? find_module_all+0x7a/0xa0
> > > [31908.550791] i915_exit+0x1a/0x87 [i915]
> > > [31908.550881] SyS_delete_module+0x264/0x2c0
> > > [31908.550971] ? free_module+0x430/0x430
> > > [31908.551064] ? trace_hardirqs_off_caller+0x16/0x110
> > > [31908.551159] ? trace_hardirqs_on_caller+0x16/0x280
> > > [31908.551256] ? trace_hardirqs_on_thunk+0x1a/0x1c
> > > [31908.551350] entry_SYSCALL_64_fastpath+0x1c/0xb1
> > > [31908.551440] RIP: 0033:0x7f1d67312ec7
> > > [31908.551520] RSP: 002b:00007ffebe34e888 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
> > > [31908.551650] RAX: ffffffffffffffda RBX: ffffffff811123f6 RCX: 00007f1d67312ec7
> > > [31908.551743] RDX: 0000000000000000 RSI: 0000000000000800 RDI: 0000560d0af476b8
> > > [31908.551837] RBP: ffff880233d87f98 R08: 0000000000000000 R09: 00007ffebe34e8b8
> > > [31908.551930] R10: 00007f1d68adf8c0 R11: 0000000000000206 R12: 0000000000000000
> > > [31908.552023] R13: 0000560d0af46440 R14: 0000000000000034 R15: 00007ffebe34d860
> > > [31908.552121] ? trace_hardirqs_off_caller+0x16/0x110
> > > [31908.552217] Object at ffff8801f7788000, in cache kmalloc-2048 size: 2048
> > > [31908.552306] Allocated:
> > > [31908.552377] PID = 3781
> > > [31908.552456] save_stack_trace+0x16/0x20
> > > [31908.552539] kasan_kmalloc+0xee/0x190
> > > [31908.552627] __kmalloc+0xdb/0x1b0
> > > [31908.552713] platform_device_alloc+0x27/0x90
> > > [31908.552804] platform_device_register_full+0x36/0x220
> > > [31908.553066] intel_lpe_audio_init+0x41e/0x570 [i915]
> > > [31908.553320] intel_audio_init+0xd/0x40 [i915]
> > > [31908.553552] i915_driver_load+0x13f5/0x1d70 [i915]
> > > [31908.553788] i915_pci_probe+0x65/0xe0 [i915]
> > > [31908.553881] pci_device_probe+0xda/0x140
> > > [31908.553969] driver_probe_device+0x400/0x660
> > > [31908.554058] __driver_attach+0x11c/0x120
> > > [31908.554147] bus_for_each_dev+0xe6/0x150
> > > [31908.554237] driver_attach+0x26/0x30
> > > [31908.554325] bus_add_driver+0x26b/0x3b0
> > > [31908.554412] driver_register+0xce/0x190
> > > [31908.554502] __pci_register_driver+0xaf/0xc0
> > > [31908.554589] 0xffffffffa0550063
> > > [31908.554675] do_one_initcall+0x8b/0x1e0
> > > [31908.554764] do_init_module+0x102/0x325
> > > [31908.554852] load_module+0x3aad/0x45e0
> > > [31908.554944] SyS_finit_module+0x169/0x1a0
> > > [31908.555033] entry_SYSCALL_64_fastpath+0x1c/0xb1
> > > [31908.555119] Freed:
> > > [31908.555188] PID = 3781
> > > [31908.555266] save_stack_trace+0x16/0x20
> > > [31908.555349] kasan_slab_free+0xb0/0x180
> > > [31908.555436] kfree+0xaa/0x170
> > > [31908.555520] platform_device_release+0x76/0x80
> > > [31908.555610] device_release+0x45/0xe0
> > > [31908.555698] kobject_put+0x11f/0x260
> > > [31908.555785] put_device+0x12/0x20
> > > [31908.555871] platform_device_unregister+0x1b/0x20
> > > [31908.556135] intel_lpe_audio_teardown+0x5c/0xb0 [i915]
> > > [31908.556390] intel_audio_deinit+0x28/0x80 [i915]
> > > [31908.556622] i915_driver_unload+0xe4/0x360 [i915]
> > > [31908.556858] i915_pci_remove+0x23/0x30 [i915]
> > > [31908.556948] pci_device_remove+0x5c/0x100
> > > [31908.557037] device_release_driver_internal+0x1db/0x2e0
> > > [31908.557129] driver_detach+0x68/0xc0
> > > [31908.557217] bus_remove_driver+0x8b/0x150
> > > [31908.557304] driver_unregister+0x3e/0x60
> > > [31908.557394] pci_unregister_driver+0x1d/0x110
> > > [31908.557653] i915_exit+0x1a/0x87 [i915]
> > > [31908.557741] SyS_delete_module+0x264/0x2c0
> > > [31908.557834] entry_SYSCALL_64_fastpath+0x1c/0xb1
> > > [31908.557919] Memory state around the buggy address:
> > > [31908.558005] ffff8801f7788200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > [31908.558127] ffff8801f7788280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > [31908.558255] >ffff8801f7788300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > [31908.558374] ^
> > > [31908.558467] ffff8801f7788380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > > [31908.558595] ffff8801f7788400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> > >
> > > Fixes: eef57324d926 ("drm/i915: setup bridge for HDMI LPE audio driver")
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> > > Cc: Jerome Anand <jerome.anand at intel.com>
> > > Cc: Jani Nikula <jani.nikula at intel.com>
> > > Cc: Takashi Iwai <tiwai at suse.de>
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >
> > Ping?
>
> Oh, this fell into a crack as it was sent just before my vacation.
>
> About the change:
>
> > > ---
> > > drivers/gpu/drm/i915/intel_lpe_audio.c | 8 ++++++--
> > > 1 file changed, 6 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_lpe_audio.c b/drivers/gpu/drm/i915/intel_lpe_audio.c
> > > index 7a5b41b1c024..32000902a204 100644
> > > --- a/drivers/gpu/drm/i915/intel_lpe_audio.c
> > > +++ b/drivers/gpu/drm/i915/intel_lpe_audio.c
> > > @@ -131,8 +131,12 @@ lpe_audio_platdev_create(struct drm_i915_private *dev_priv)
> > >
> > > static void lpe_audio_platdev_destroy(struct drm_i915_private *dev_priv)
> > > {
> > > - platform_device_unregister(dev_priv->lpe_audio.platdev);
> > > - kfree(dev_priv->lpe_audio.platdev->dev.dma_mask);
> > > + struct platform_device *platdev = dev_priv->lpe_audio.platdev;
> > > +
> > > + kfree(platdev->dev.dma_mask);
> > > + platdev->dev.dma_mask = NULL;
> > > +
> > > + platform_device_unregister(platdev);
>
> I'm not sure whether it's good idea to fiddle dma_mask bits before the
> unregister call. Interestingly, this is the only driver that calls
> kfree() for pdev's dma_mask. Either we do something wrong, or
> everyone forgot this?
Afaict, everyone else chose the blissful ignorance strategy and we are
the only fools to try and free the dma_mask.
Would you feel more comfortable with:
void *mask = platdev->dev.dma_mask;
platform_device_unregister(platdev);
/* XXX see platform_device_register_full():
* "This memory isn't freed when the device is put."
* It's not clear why it hasn't been fixed in a decade...
*/
kfree(mask);
--
Chris Wilson, Intel Open Source Technology Centre
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