2020-11-16 11:08:23

by Colin King

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Subject: [PATCH][next] drm/atomic: avoid null pointer dereference on pointer crtc

From: Colin Ian King <[email protected]>

Since moving to the new debug helper functions we now have a debug message
that dereferences crtc to print a kernel debug message when crtc is null
and so this debug message will now cause a null pointer dereference. Since
this is a debug message it probably is just simplest to fix this by just
removing the debug message altogether.

Addresses-Coverity: ("Dereference after null check")
Fixes: e3aae683e861 ("drm: convert drm_atomic_uapi.c to new debug helpers")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/gpu/drm/drm_atomic_uapi.c | 5 -----
1 file changed, 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
index 9df7f2a170e3..3fd84590560a 100644
--- a/drivers/gpu/drm/drm_atomic_uapi.c
+++ b/drivers/gpu/drm/drm_atomic_uapi.c
@@ -338,11 +338,6 @@ drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
"Link [CONNECTOR:%d:%s] state %p to [CRTC:%d:%s]\n",
connector->base.id, connector->name,
conn_state, crtc->base.id, crtc->name);
- } else {
- drm_dbg_atomic(crtc->dev,
- "Link [CONNECTOR:%d:%s] state %p to [NOCRTC]\n",
- connector->base.id, connector->name,
- conn_state);
}

return 0;
--
2.28.0


2020-11-16 11:10:15

by Simon Ser

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Subject: Re: [PATCH][next] drm/atomic: avoid null pointer dereference on pointer crtc

On Monday, November 16, 2020 12:03 PM, Colin King <[email protected]> wrote:

> From: Colin Ian King [email protected]
>
> Since moving to the new debug helper functions we now have a debug message
> that dereferences crtc to print a kernel debug message when crtc is null
> and so this debug message will now cause a null pointer dereference. Since
> this is a debug message it probably is just simplest to fix this by just
> removing the debug message altogether.

NACK. This removes the log altogether instead of fixing it.

A fix has already been pushed to drm-misc-next: 0003b687ee6d ("drm: fix
oops in drm_atomic_set_crtc_for_connector").

2020-11-16 11:33:09

by Colin King

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Subject: Re: [PATCH][next] drm/atomic: avoid null pointer dereference on pointer crtc

On 16/11/2020 11:08, Simon Ser wrote:
> On Monday, November 16, 2020 12:03 PM, Colin King <[email protected]> wrote:
>
>> From: Colin Ian King [email protected]
>>
>> Since moving to the new debug helper functions we now have a debug message
>> that dereferences crtc to print a kernel debug message when crtc is null
>> and so this debug message will now cause a null pointer dereference. Since
>> this is a debug message it probably is just simplest to fix this by just
>> removing the debug message altogether.
>
> NACK. This removes the log altogether instead of fixing it.
>
> A fix has already been pushed to drm-misc-next: 0003b687ee6d ("drm: fix
> oops in drm_atomic_set_crtc_for_connector").
>
Good to see this has already been fixed. Thanks.

Colin