Patchwork [3.5.y.z,extended,stable] Patch "drm: fix a use-after-free when GPU acceleration disabled" has been added to staging queue

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Submitter Luis Henriques
Date June 12, 2013, 1:15 p.m.
Message ID <1371042932-11202-1-git-send-email-luis.henriques@canonical.com>
Download mbox | patch
Permalink /patch/250772/
State New
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Luis Henriques - June 12, 2013, 1:15 p.m.
This is a note to let you know that I have just added a patch titled

    drm: fix a use-after-free when GPU acceleration disabled

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From 984afdbbbf84362cf50cda1ce96c1d11adf68444 Mon Sep 17 00:00:00 2001
From: Huacai Chen <chenhc@lemote.com>
Date: Tue, 21 May 2013 06:23:43 +0000
Subject: [PATCH] drm: fix a use-after-free when GPU acceleration disabled
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

commit b7ea85a4fed37835eec78a7be3039c8dc22b8178 upstream.

When GPU acceleration is disabled, drm_vblank_cleanup() will free the
vblank-related data, such as vblank_refcount, vblank_inmodeset, etc.
But we found that drm_vblank_post_modeset() may be called after the
cleanup, which use vblank_refcount and vblank_inmodeset. And this will
cause a kernel panic.

Fix this by return immediately if dev->num_crtcs is zero. This is the
same thing that drm_vblank_pre_modeset() does.

Call trace of a drm_vblank_post_modeset() after drm_vblank_cleanup():
[   62.628906] [<ffffffff804868d0>] drm_vblank_post_modeset+0x34/0xb4
[   62.628906] [<ffffffff804c7008>] atombios_crtc_dpms+0xb4/0x174
[   62.628906] [<ffffffff804c70e0>] atombios_crtc_commit+0x18/0x38
[   62.628906] [<ffffffff8047f038>] drm_crtc_helper_set_mode+0x304/0x3cc
[   62.628906] [<ffffffff8047f92c>] drm_crtc_helper_set_config+0x6d8/0x988
[   62.628906] [<ffffffff8047dd40>] drm_fb_helper_set_par+0x94/0x104
[   62.628906] [<ffffffff80439d14>] fbcon_init+0x424/0x57c
[   62.628906] [<ffffffff8046a638>] visual_init+0xb8/0x118
[   62.628906] [<ffffffff8046b9f8>] take_over_console+0x238/0x384
[   62.628906] [<ffffffff80436df8>] fbcon_takeover+0x7c/0xdc
[   62.628906] [<ffffffff8024fa20>] notifier_call_chain+0x44/0x94
[   62.628906] [<ffffffff8024fcbc>] __blocking_notifier_call_chain+0x48/0x68
[   62.628906] [<ffffffff8042d990>] register_framebuffer+0x228/0x260
[   62.628906] [<ffffffff8047e010>] drm_fb_helper_single_fb_probe+0x260/0x314
[   62.628906] [<ffffffff8047e2c4>] drm_fb_helper_initial_config+0x200/0x234
[   62.628906] [<ffffffff804e5560>] radeon_fbdev_init+0xd4/0xf4
[   62.628906] [<ffffffff804e0e08>] radeon_modeset_init+0x9bc/0xa18
[   62.628906] [<ffffffff804bfc14>] radeon_driver_load_kms+0xdc/0x12c
[   62.628906] [<ffffffff8048b548>] drm_get_pci_dev+0x148/0x238
[   62.628906] [<ffffffff80423564>] local_pci_probe+0x5c/0xd0
[   62.628906] [<ffffffff80241ac4>] work_for_cpu_fn+0x1c/0x30
[   62.628906] [<ffffffff802427c8>] process_one_work+0x274/0x3bc
[   62.628906] [<ffffffff80242934>] process_scheduled_works+0x24/0x44
[   62.628906] [<ffffffff8024515c>] worker_thread+0x31c/0x3f4
[   62.628906] [<ffffffff802497a8>] kthread+0x88/0x90
[   62.628906] [<ffffffff80206794>] kernel_thread_helper+0x10/0x18

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Binbin Zhou <zhoubb@lemote.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>
Signed-off-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/gpu/drm/drm_irq.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--
1.8.1.2

Patch

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index c798eea..c7a1348 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -981,7 +981,7 @@  EXPORT_SYMBOL(drm_vblank_off);
  */
 void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
 {
-	/* vblank is not initialized (IRQ not installed ?) */
+	/* vblank is not initialized (IRQ not installed ?), or has been freed */
 	if (!dev->num_crtcs)
 		return;
 	/*
@@ -1003,6 +1003,10 @@  void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
 {
 	unsigned long irqflags;

+	/* vblank is not initialized (IRQ not installed ?), or has been freed */
+	if (!dev->num_crtcs)
+		return;
+
 	if (dev->vblank_inmodeset[crtc]) {
 		spin_lock_irqsave(&dev->vbl_lock, irqflags);
 		dev->vblank_disable_allowed = 1;