[PATCH AUTOSEL 4.19 01/57] drm/cirrus: Use drm_framebuffer_put to avoid kernel oops in clean-up

Sasha Levin
2019-03-30T01:41:16Z

From: Thomas Zimmermann <tzimmermann@suse.de>

[ Upstream commit abf7b30d7f61d981bfcca65d1e8331b27021b475 ]

In the Cirrus driver, the regular clean-up code also performs the clean-up
of a failed initialization. If the fbdev's framebuffer was not initialized,
the clean-up will fail within drm_framebuffer_unregister_private. Booting
with cirrus.bpp=16 triggers this bug.

The framebuffer is currently stored directly within struct cirrus_fbdev. To
fix the bug, we turn it into a pointer that is only set for initialized
framebuffers. The fbdev's clean-up code skips uninitialized framebuffers.

The memory for struct drm_framebuffer is allocated dynamically. This requires
additional error handling within cirrusfb_create. The framebuffer clean-up is
now performed by drm_framebuffer_put, which also frees the data strcuture's
memory.

Link: https://bugzilla.suse.com/show_bug.cgi?id=1101822
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20180720112743.27159-1-tzimmermann@suse.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/cirrus/cirrus_drv.h | 2 +-
drivers/gpu/drm/cirrus/cirrus_fbdev.c | 48 +++++++++++++++------------
drivers/gpu/drm/cirrus/cirrus_mode.c | 2 +-
3 files changed, 29 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/cirrus/cirrus_drv.h b/drivers/gpu/drm/cirrus/cirrus_drv.h
index ce9db7aab225..a29f87e98d9d 100644
--- a/drivers/gpu/drm/cirrus/cirrus_drv.h
+++ b/drivers/gpu/drm/cirrus/cirrus_drv.h
@@ -146,7 +146,7 @@ struct cirrus_device {

struct cirrus_fbdev {
struct drm_fb_helper helper;
- struct drm_framebuffer gfb;
+ struct drm_framebuffer *gfb;
void *sysram;
int size;
int x1, y1, x2, y2; /* dirty rect */
diff --git a/drivers/gpu/drm/cirrus/cirrus_fbdev.c b/drivers/gpu/drm/cirrus/cirrus_fbdev.c
index b643ac92801c..82cc82e0bd80 100644
--- a/drivers/gpu/drm/cirrus/cirrus_fbdev.c
+++ b/drivers/gpu/drm/cirrus/cirrus_fbdev.c
@@ -22,14 +22,14 @@ static void cirrus_dirty_update(struct cirrus_fbdev *afbdev,
struct drm_gem_object *obj;
struct cirrus_bo *bo;
int src_offset, dst_offset;
- int bpp = afbdev->gfb.format->cpp[0];
+ int bpp = afbdev->gfb->format->cpp[0];
int ret = -EBUSY;
bool unmap = false;
bool store_for_later = false;
int x2, y2;
unsigned long flags;

- obj = afbdev->gfb.obj[0];
+ obj = afbdev->gfb->obj[0];
bo = gem_to_cirrus_bo(obj);

/*
@@ -82,7 +82,7 @@ static void cirrus_dirty_update(struct cirrus_fbdev *afbdev,
}
for (i = y; i < y + height; i++) {
/* assume equal stride for now */
- src_offset = dst_offset = i * afbdev->gfb.pitches[0] + (x * bpp);
+ src_offset = dst_offset = i * afbdev->gfb->pitches[0] + (x * bpp);
memcpy_toio(bo->kmap.virtual + src_offset, afbdev->sysram + src_offset, width * bpp);

}
@@ -192,23 +192,26 @@ static int cirrusfb_create(struct drm_fb_helper *helper,
return -ENOMEM;

info = drm_fb_helper_alloc_fbi(helper);
- if (IS_ERR(info))
- return PTR_ERR(info);
+ if (IS_ERR(info)) {
+ ret = PTR_ERR(info);
+ goto err_vfree;
+ }

info->par = gfbdev;

- ret = cirrus_framebuffer_init(cdev->dev, &gfbdev->gfb, &mode_cmd, gobj);
+ fb = kzalloc(sizeof(*fb), GFP_KERNEL);
+ if (!fb) {
+ ret = -ENOMEM;
+ goto err_drm_gem_object_put_unlocked;
+ }
+
+ ret = cirrus_framebuffer_init(cdev->dev, fb, &mode_cmd, gobj);
if (ret)
- return ret;
+ goto err_kfree;

gfbdev->sysram = sysram;
gfbdev->size = size;
-
- fb = &gfbdev->gfb;
- if (!fb) {
- DRM_INFO("fb is NULL\n");
- return -EINVAL;
- }
+ gfbdev->gfb = fb;

/* setup helper */
gfbdev->helper.fb = fb;
@@ -241,24 +244,27 @@ static int cirrusfb_create(struct drm_fb_helper *helper,
DRM_INFO(" pitch is %d\n", fb->pitches[0]);

return 0;
+
+err_kfree:
+ kfree(fb);
+err_drm_gem_object_put_unlocked:
+ drm_gem_object_put_unlocked(gobj);
+err_vfree:
+ vfree(sysram);
+ return ret;
}

static int cirrus_fbdev_destroy(struct drm_device *dev,
struct cirrus_fbdev *gfbdev)
{
- struct drm_framebuffer *gfb = &gfbdev->gfb;
+ struct drm_framebuffer *gfb = gfbdev->gfb;

drm_fb_helper_unregister_fbi(&gfbdev->helper);

- if (gfb->obj[0]) {
- drm_gem_object_put_unlocked(gfb->obj[0]);
- gfb->obj[0] = NULL;
- }
-
vfree(gfbdev->sysram);
drm_fb_helper_fini(&gfbdev->helper);
- drm_framebuffer_unregister_private(gfb);
- drm_framebuffer_cleanup(gfb);
+ if (gfb)
+ drm_framebuffer_put(gfb);

return 0;
}
diff --git a/drivers/gpu/drm/cirrus/cirrus_mode.c b/drivers/gpu/drm/cirrus/cirrus_mode.c
index 336bfda40125..90a4e641d3fb 100644
--- a/drivers/gpu/drm/cirrus/cirrus_mode.c
+++ b/drivers/gpu/drm/cirrus/cirrus_mode.c
@@ -127,7 +127,7 @@ static int cirrus_crtc_do_set_base(struct drm_crtc *crtc,
return ret;
}

- if (&cdev->mode_info.gfbdev->gfb == crtc->primary->fb) {
+ if (cdev->mode_info.gfbdev->gfb == crtc->primary->fb) {
/* if pushing console in kmap it */
ret = ttm_bo_kmap(&bo->bo, 0, bo->bo.num_pages, &bo->kmap);
if (ret)
--
2.19.1