From: Colin Ian King <[email protected]>
The pointer workload is dereferenced before it is null checked, hence
there is a potential for a null pointer dereference on workload. Fix
this by only dereferencing workload after it is null checked.
Detected by CoverityScan, CID#1466017 ("Dereference before null check")
Fixes: fa3dd623e559 ("drm/i915/gvt: keep oa config in shadow ctx")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/gpu/drm/i915/gvt/scheduler.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 068126404151..f3010e365a48 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -60,9 +60,9 @@ static void set_context_pdp_root_pointer(
static void sr_oa_regs(struct intel_vgpu_workload *workload,
u32 *reg_state, bool save)
{
- struct drm_i915_private *dev_priv = workload->vgpu->gvt->dev_priv;
- u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
- u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
+ struct drm_i915_private *dev_priv;
+ u32 ctx_oactxctrl;
+ u32 ctx_flexeu0;
int i = 0;
u32 flex_mmio[] = {
i915_mmio_reg_offset(EU_PERF_CNTL0),
@@ -77,6 +77,10 @@ static void sr_oa_regs(struct intel_vgpu_workload *workload,
if (!workload || !reg_state || workload->ring_id != RCS)
return;
+ dev_priv = workload->vgpu->gvt->dev_priv;
+ ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
+ ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
+
if (save) {
workload->oactxctrl = reg_state[ctx_oactxctrl + 1];
--
2.15.1
On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> The pointer workload is dereferenced before it is null checked, hence
> there is a potential for a null pointer dereference on workload. Fix
> this by only dereferencing workload after it is null checked.
>
> Detected by CoverityScan, CID#1466017 ("Dereference before null check")
Maybe true, but is it possible for workload to be null?
Maybe the null test should be removed instead.
> Fixes: fa3dd623e559 ("drm/i915/gvt: keep oa config in shadow ctx")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> drivers/gpu/drm/i915/gvt/scheduler.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> index 068126404151..f3010e365a48 100644
> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> @@ -60,9 +60,9 @@ static void set_context_pdp_root_pointer(
> static void sr_oa_regs(struct intel_vgpu_workload *workload,
> u32 *reg_state, bool save)
> {
> - struct drm_i915_private *dev_priv = workload->vgpu->gvt->dev_priv;
> - u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
> - u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
> + struct drm_i915_private *dev_priv;
> + u32 ctx_oactxctrl;
> + u32 ctx_flexeu0;
> int i = 0;
> u32 flex_mmio[] = {
> i915_mmio_reg_offset(EU_PERF_CNTL0),
> @@ -77,6 +77,10 @@ static void sr_oa_regs(struct intel_vgpu_workload *workload,
> if (!workload || !reg_state || workload->ring_id != RCS)
> return;
>
> + dev_priv = workload->vgpu->gvt->dev_priv;
> + ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
> + ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
> +
> if (save) {
> workload->oactxctrl = reg_state[ctx_oactxctrl + 1];
>
On 21/03/18 19:09, Joe Perches wrote:
> On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
>> From: Colin Ian King <[email protected]>
>>
>> The pointer workload is dereferenced before it is null checked, hence
>> there is a potential for a null pointer dereference on workload. Fix
>> this by only dereferencing workload after it is null checked.
>>
>> Detected by CoverityScan, CID#1466017 ("Dereference before null check")
>
> Maybe true, but is it possible for workload to be null?
> Maybe the null test should be removed instead.
From what I understand from the static analysis, there may be a
potential for workload to be null, I couldn't rule it out so I went with
the more paranoid stance of keeping the null check in.
>
>> Fixes: fa3dd623e559 ("drm/i915/gvt: keep oa config in shadow ctx")
>> Signed-off-by: Colin Ian King <[email protected]>
>> ---
>> drivers/gpu/drm/i915/gvt/scheduler.c | 10 +++++++---
>> 1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
>> index 068126404151..f3010e365a48 100644
>> --- a/drivers/gpu/drm/i915/gvt/scheduler.c
>> +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
>> @@ -60,9 +60,9 @@ static void set_context_pdp_root_pointer(
>> static void sr_oa_regs(struct intel_vgpu_workload *workload,
>> u32 *reg_state, bool save)
>> {
>> - struct drm_i915_private *dev_priv = workload->vgpu->gvt->dev_priv;
>> - u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
>> - u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
>> + struct drm_i915_private *dev_priv;
>> + u32 ctx_oactxctrl;
>> + u32 ctx_flexeu0;
>> int i = 0;
>> u32 flex_mmio[] = {
>> i915_mmio_reg_offset(EU_PERF_CNTL0),
>> @@ -77,6 +77,10 @@ static void sr_oa_regs(struct intel_vgpu_workload *workload,
>> if (!workload || !reg_state || workload->ring_id != RCS)
>> return;
>>
>> + dev_priv = workload->vgpu->gvt->dev_priv;
>> + ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
>> + ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
>> +
>> if (save) {
>> workload->oactxctrl = reg_state[ctx_oactxctrl + 1];
>>
On Wed, 2018-03-21 at 19:18 +0000, Colin Ian King wrote:
> On 21/03/18 19:09, Joe Perches wrote:
> > On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
> > > From: Colin Ian King <[email protected]>
> > >
> > > The pointer workload is dereferenced before it is null checked, hence
> > > there is a potential for a null pointer dereference on workload. Fix
> > > this by only dereferencing workload after it is null checked.
> > >
> > > Detected by CoverityScan, CID#1466017 ("Dereference before null check")
> >
> > Maybe true, but is it possible for workload to be null?
> > Maybe the null test should be removed instead.
>
> From what I understand from the static analysis, there may be a
> potential for workload to be null, I couldn't rule it out so I went with
> the more paranoid stance of keeping the null check in.
workload cannot be null here.
Look at the uses of sr_oa_regs and see that
workload has already been dereferenced.
> >
> > > Fixes: fa3dd623e559 ("drm/i915/gvt: keep oa config in shadow ctx")
> > > Signed-off-by: Colin Ian King <[email protected]>
> > > ---
> > > drivers/gpu/drm/i915/gvt/scheduler.c | 10 +++++++---
> > > 1 file changed, 7 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
> > > index 068126404151..f3010e365a48 100644
> > > --- a/drivers/gpu/drm/i915/gvt/scheduler.c
> > > +++ b/drivers/gpu/drm/i915/gvt/scheduler.c
> > > @@ -60,9 +60,9 @@ static void set_context_pdp_root_pointer(
> > > static void sr_oa_regs(struct intel_vgpu_workload *workload,
> > > u32 *reg_state, bool save)
> > > {
> > > - struct drm_i915_private *dev_priv = workload->vgpu->gvt->dev_priv;
> > > - u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
> > > - u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
> > > + struct drm_i915_private *dev_priv;
> > > + u32 ctx_oactxctrl;
> > > + u32 ctx_flexeu0;
> > > int i = 0;
> > > u32 flex_mmio[] = {
> > > i915_mmio_reg_offset(EU_PERF_CNTL0),
> > > @@ -77,6 +77,10 @@ static void sr_oa_regs(struct intel_vgpu_workload *workload,
> > > if (!workload || !reg_state || workload->ring_id != RCS)
> > > return;
> > >
> > > + dev_priv = workload->vgpu->gvt->dev_priv;
> > > + ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
> > > + ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
> > > +
> > > if (save) {
> > > workload->oactxctrl = reg_state[ctx_oactxctrl + 1];
> > >
>
>
On 21/03/18 19:23, Chris Wilson wrote:
> Quoting Colin Ian King (2018-03-21 19:18:28)
>> On 21/03/18 19:09, Joe Perches wrote:
>>> On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
>>>> From: Colin Ian King <[email protected]>
>>>>
>>>> The pointer workload is dereferenced before it is null checked, hence
>>>> there is a potential for a null pointer dereference on workload. Fix
>>>> this by only dereferencing workload after it is null checked.
>>>>
>>>> Detected by CoverityScan, CID#1466017 ("Dereference before null check")
>>>
>>> Maybe true, but is it possible for workload to be null?
>>> Maybe the null test should be removed instead.
>>
>> From what I understand from the static analysis, there may be a
>> potential for workload to be null, I couldn't rule it out so I went with
>> the more paranoid stance of keeping the null check in.
>
> Not sr_oa_regs() problem if workload is NULL, that's the callers. I
> reviewed the identical patch yesterday, and we ended up with removing
> the NULL checks, just keeping the workload->id != RCS.
> -Chris
>
Ah, OK, thanks for the clarification Chris.
Quoting Colin Ian King (2018-03-21 19:18:28)
> On 21/03/18 19:09, Joe Perches wrote:
> > On Wed, 2018-03-21 at 19:06 +0000, Colin King wrote:
> >> From: Colin Ian King <[email protected]>
> >>
> >> The pointer workload is dereferenced before it is null checked, hence
> >> there is a potential for a null pointer dereference on workload. Fix
> >> this by only dereferencing workload after it is null checked.
> >>
> >> Detected by CoverityScan, CID#1466017 ("Dereference before null check")
> >
> > Maybe true, but is it possible for workload to be null?
> > Maybe the null test should be removed instead.
>
> From what I understand from the static analysis, there may be a
> potential for workload to be null, I couldn't rule it out so I went with
> the more paranoid stance of keeping the null check in.
Not sr_oa_regs() problem if workload is NULL, that's the callers. I
reviewed the identical patch yesterday, and we ended up with removing
the NULL checks, just keeping the workload->id != RCS.
-Chris