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Subject[PATCH V2] drm/arm/malidp: fix a possible null pointer dereference
Date
In malidp_mw_connector_reset, new memory is allocated with kzalloc, but 
no check is performed. In order to prevent null pointer dereferencing,
ensure that mw_state is checked before calling
__drm_atomic_helper_connector_reset.

Fixes: 8cbc5caf36ef ("drm: mali-dp: Add writeback connector")
Signed-off-by: Huai-Yuan Liu <qq810974084@gmail.com>
---
V2:
* In patch V2, we additionally set connector->state to NULL. In this way
we can ensure that there is no state pointing to freed memory.
Thanks to Liviu Dudau for helpful suggestion.
---
drivers/gpu/drm/arm/malidp_mw.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/arm/malidp_mw.c b/drivers/gpu/drm/arm/malidp_mw.c
index 626709bec6f5..2577f0cef8fc 100644
--- a/drivers/gpu/drm/arm/malidp_mw.c
+++ b/drivers/gpu/drm/arm/malidp_mw.c
@@ -72,7 +72,10 @@ static void malidp_mw_connector_reset(struct drm_connector *connector)
__drm_atomic_helper_connector_destroy_state(connector->state);

kfree(connector->state);
- __drm_atomic_helper_connector_reset(connector, &mw_state->base);
+ connector->state = NULL;
+
+ if (mw_state)
+ __drm_atomic_helper_connector_reset(connector, &mw_state->base);
}

static enum drm_connector_status
--
2.34.1

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