On Thu, Nov 05, 2020 at 08:02:56PM +0100, Thomas Zimmermann wrote:
> 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 <tzimmerm...@suse.de>
> Fixes: 5c49fd3aa0ab ("gma500: Add the core DRM files and headers")
> Cc: Alan Cox <a...@linux.intel.com>
> Cc: Dave Airlie <airl...@redhat.com>
> Cc: Patrik Jakobsson <patrik.r.jakobs...@gmail.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: sta...@vger.kernel.org#v3.3+
Reviewed-by: Daniel Vetter <daniel.vet...@ffwll.ch>
> ---
> drivers/gpu/drm/gma500/psb_irq.c | 34 +++++++++++---------------------
> 1 file changed, 12 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/gma500/psb_irq.c
> b/drivers/gpu/drm/gma500/psb_irq.c
> index 15eb3770d817..361e3a0c5ab6 100644
> --- a/drivers/gpu/drm/gma500/psb_irq.c
> +++ b/drivers/gpu/drm/gma500/psb_irq.c
> @@ -347,6 +347,7 @@ int psb_irq_postinstall(struct drm_device *dev)
> {
> struct drm_psb_private *dev_priv = dev->dev_private;
> unsigned long irqflags;
> + unsigned int i;
>
> spin_lock_irqsave(&dev_priv->irqmask_lock, irqflags);
>
> @@ -359,20 +360,12 @@ int psb_irq_postinstall(struct drm_device *dev)
> 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);
> @@ -385,6 +378,7 @@ void psb_irq_uninstall(struct drm_device *dev)
> {
> struct drm_psb_private *dev_priv = dev->dev_private;
> unsigned long irqflags;
> + unsigned int i;
>
> spin_lock_irqsave(&dev_priv->irqmask_lock, irqflags);
>
> @@ -393,14 +387,10 @@ void psb_irq_uninstall(struct drm_device *dev)
>
> 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 |
> --
> 2.29.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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