[PATCH v2] gpu: radeon: fix a potential NULL-pointer dereference

From: Kangjie Lu
Date: Mon Mar 25 2019 - 17:06:25 EST


In case alloc_workqueue fails, the fix frees memory and
returns -ENOMEM to avoid potential NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
---
v2: use radeon_crtc_destroy to properly clean up resources as
suggested by Michel DÃnzer <michel@xxxxxxxxxxx>
---
drivers/gpu/drm/radeon/radeon_display.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index aa898c699101..3c6d3289316b 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -663,7 +663,7 @@ static const struct drm_crtc_funcs radeon_crtc_funcs = {
.page_flip_target = radeon_crtc_page_flip_target,
};

-static void radeon_crtc_init(struct drm_device *dev, int index)
+static int radeon_crtc_init(struct drm_device *dev, int index)
{
struct radeon_device *rdev = dev->dev_private;
struct radeon_crtc *radeon_crtc;
@@ -671,13 +671,18 @@ static void radeon_crtc_init(struct drm_device *dev, int index)

radeon_crtc = kzalloc(sizeof(struct radeon_crtc) + (RADEONFB_CONN_LIMIT * sizeof(struct drm_connector *)), GFP_KERNEL);
if (radeon_crtc == NULL)
- return;
+ return -ENOMEM;

drm_crtc_init(dev, &radeon_crtc->base, &radeon_crtc_funcs);

drm_mode_crtc_set_gamma_size(&radeon_crtc->base, 256);
radeon_crtc->crtc_id = index;
radeon_crtc->flip_queue = alloc_workqueue("radeon-crtc", WQ_HIGHPRI, 0);
+ if (!radeon_crtc->flip_queue) {
+ DRM_ERROR("failed to allocate the flip queue\n");
+ radeon_crtc_destroy(&radeon_crtc->base);
+ return -ENOMEM;
+ }
rdev->mode_info.crtcs[index] = radeon_crtc;

if (rdev->family >= CHIP_BONAIRE) {
@@ -706,6 +711,8 @@ static void radeon_crtc_init(struct drm_device *dev, int index)
radeon_atombios_init_crtc(dev, radeon_crtc);
else
radeon_legacy_init_crtc(dev, radeon_crtc);
+
+ return 0;
}

static const char *encoder_names[38] = {
@@ -1612,7 +1619,9 @@ int radeon_modeset_init(struct radeon_device *rdev)

/* allocate crtcs */
for (i = 0; i < rdev->num_crtc; i++) {
- radeon_crtc_init(rdev->ddev, i);
+ ret = radeon_crtc_init(rdev->ddev, i);
+ if (ret)
+ return ret;
}

/* okay we should have all the bios connectors */
--
2.17.1