[PATCH] drm/i915/display: fix missing null check on allocated dsb object

[Colin King]

From: Colin Ian King <colin.king at canonical.com>

Currently there is no null check for a failed memory allocation
on the dsb object and without this a null pointer dereference
error can occur. Fix this by adding a null check.

Note: added a drm_err message in keeping with the error message style
in the function.

Addresses-Coverity: ("Dereference null return")
Fixes: afeda4f3b1c8 ("drm/i915/dsb: Pre allocate and late cleanup of cmd buffer")
Signed-off-by: Colin Ian King <colin.king at canonical.com>
---
 drivers/gpu/drm/i915/display/intel_dsb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index 24e6d63e2d47..566fa72427b3 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -271,6 +271,10 @@ void intel_dsb_prepare(struct intel_crtc_state *crtc_state)
 		return;
 
 	dsb = kmalloc(sizeof(*dsb), GFP_KERNEL);
+	if (!dsb) {
+		drm_err(&i915->drm, "DSB object creation failed\n");
+		return;
+	}
 
 	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
 
-- 
2.27.0.rc0