[PATCH 4.9 49/78] drm/gma500: Fix out-of-bounds access to struct drm_device.vblank[]

Greg Kroah-Hartman
2020-11-17T16:10:42Z

From: Thomas Zimmermann <tzimmermann@suse.de>

commit 06ad8d339524bf94b89859047822c31df6ace239 upstream.

The gma500 driver expects 3 pipelines in several it's IRQ functions.
Accessing struct drm_device.vblank[], this fails with devices that only
have 2 pipelines. An example KASAN report is shown below.

[ 62.267688] ==================================================================
[ 62.268856] BUG: KASAN: slab-out-of-bounds in psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.269450] Read of size 1 at addr ffff8880012bc6d0 by task systemd-udevd/285
[ 62.269949]
[ 62.270192] CPU: 0 PID: 285 Comm: systemd-udevd Tainted: G E 5.10.0-rc1-1-default+ #572
[ 62.270807] Hardware name: /DN2800MT, BIOS MTCDT10N.86A.0164.2012.1213.1024 12/13/2012
[ 62.271366] Call Trace:
[ 62.271705] dump_stack+0xae/0xe5
[ 62.272180] print_address_description.constprop.0+0x17/0xf0
[ 62.272987] ? psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.273474] __kasan_report.cold+0x20/0x38
[ 62.273989] ? psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.274460] kasan_report+0x3a/0x50
[ 62.274891] psb_irq_postinstall+0x250/0x3c0 [gma500_gfx]
[ 62.275380] drm_irq_install+0x131/0x1f0
<...>
[ 62.300751] Allocated by task 285:
[ 62.301223] kasan_save_stack+0x1b/0x40
[ 62.301731] __kasan_kmalloc.constprop.0+0xbf/0xd0
[ 62.302293] drmm_kmalloc+0x55/0x100
[ 62.302773] drm_vblank_init+0x77/0x210

Resolve the issue by only handling vblank entries up to the number of
CRTCs.

I'm adding a Fixes tag for reference, although the bug has been present
since the driver's initial commit.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Fixes: 5c49fd3aa0ab ("gma500: Add the core DRM files and headers")
Cc: Alan Cox <alan@linux.intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org#v3.3+
Link: https://patchwork.freedesktop.org/patch/msgid/20201105190256.3893-1-tzimmermann@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpu/drm/gma500/psb_irq.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)

--- a/drivers/gpu/drm/gma500/psb_irq.c
+++ b/drivers/gpu/drm/gma500/psb_irq.c
@@ -350,6 +350,7 @@ int psb_irq_postinstall(struct drm_devic
{
struct drm_psb_private *dev_priv = dev->dev_private;
unsigned long irqflags;
+ unsigned int i;

spin_lock_irqsave(&dev_priv->irqmask_lock, irqflags);

@@ -362,20 +363,12 @@ int psb_irq_postinstall(struct drm_devic
PSB_WVDC32(dev_priv->vdc_irq_mask, PSB_INT_ENABLE_R);
PSB_WVDC32(0xFFFFFFFF, PSB_HWSTAM);

- if (dev->vblank[0].enabled)
- psb_enable_pipestat(dev_priv, 0, PIPE_VBLANK_INTERRUPT_ENABLE);
- else
- psb_disable_pipestat(dev_priv, 0, PIPE_VBLANK_INTERRUPT_ENABLE);
-
- if (dev->vblank[1].enabled)
- psb_enable_pipestat(dev_priv, 1, PIPE_VBLANK_INTERRUPT_ENABLE);
- else
- psb_disable_pipestat(dev_priv, 1, PIPE_VBLANK_INTERRUPT_ENABLE);
-
- if (dev->vblank[2].enabled)
- psb_enable_pipestat(dev_priv, 2, PIPE_VBLANK_INTERRUPT_ENABLE);
- else
- psb_disable_pipestat(dev_priv, 2, PIPE_VBLANK_INTERRUPT_ENABLE);
+ for (i = 0; i < dev->num_crtcs; ++i) {
+ if (dev->vblank[i].enabled)
+ psb_enable_pipestat(dev_priv, i, PIPE_VBLANK_INTERRUPT_ENABLE);
+ else
+ psb_disable_pipestat(dev_priv, i, PIPE_VBLANK_INTERRUPT_ENABLE);
+ }

if (dev_priv->ops->hotplug_enable)
dev_priv->ops->hotplug_enable(dev, true);
@@ -388,6 +381,7 @@ void psb_irq_uninstall(struct drm_device
{
struct drm_psb_private *dev_priv = dev->dev_private;
unsigned long irqflags;
+ unsigned int i;

spin_lock_irqsave(&dev_priv->irqmask_lock, irqflags);

@@ -396,14 +390,10 @@ void psb_irq_uninstall(struct drm_device

PSB_WVDC32(0xFFFFFFFF, PSB_HWSTAM);

- if (dev->vblank[0].enabled)
- psb_disable_pipestat(dev_priv, 0, PIPE_VBLANK_INTERRUPT_ENABLE);
-
- if (dev->vblank[1].enabled)
- psb_disable_pipestat(dev_priv, 1, PIPE_VBLANK_INTERRUPT_ENABLE);
-
- if (dev->vblank[2].enabled)
- psb_disable_pipestat(dev_priv, 2, PIPE_VBLANK_INTERRUPT_ENABLE);
+ for (i = 0; i < dev->num_crtcs; ++i) {
+ if (dev->vblank[i].enabled)
+ psb_disable_pipestat(dev_priv, i, PIPE_VBLANK_INTERRUPT_ENABLE);
+ }

dev_priv->vdc_irq_mask &= _PSB_IRQ_SGX_FLAG |
_PSB_IRQ_MSVDX_FLAG |