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drm/nv04/crtc: Bail out if FB is not bound to crtc

This commit resolves a possible 'NULL pointer dereference'
It uses the same approach as radeon, intel and nouveau/nv50

Fixes bug 'Nouveau: Kernel oops when unplugging external monitor'
https://bugs.freedesktop.org/show_bug.cgi?id=40336

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
Emil Velikov 2011-08-25 21:36:51 +01:00 committed by Ben Skeggs
parent 1bf2706601
commit 0e83bb4eee

View File

@ -781,11 +781,20 @@ nv04_crtc_do_mode_set_base(struct drm_crtc *crtc,
struct drm_device *dev = crtc->dev;
struct drm_nouveau_private *dev_priv = dev->dev_private;
struct nv04_crtc_reg *regp = &dev_priv->mode_reg.crtc_reg[nv_crtc->index];
struct drm_framebuffer *drm_fb = nv_crtc->base.fb;
struct nouveau_framebuffer *fb = nouveau_framebuffer(drm_fb);
struct drm_framebuffer *drm_fb;
struct nouveau_framebuffer *fb;
int arb_burst, arb_lwm;
int ret;
NV_DEBUG_KMS(dev, "index %d\n", nv_crtc->index);
/* no fb bound */
if (!atomic && !crtc->fb) {
NV_DEBUG_KMS(dev, "No FB bound\n");
return 0;
}
/* If atomic, we want to switch to the fb we were passed, so
* now we update pointers to do that. (We don't pin; just
* assume we're already pinned and update the base address.)
@ -794,6 +803,8 @@ nv04_crtc_do_mode_set_base(struct drm_crtc *crtc,
drm_fb = passed_fb;
fb = nouveau_framebuffer(passed_fb);
} else {
drm_fb = crtc->fb;
fb = nouveau_framebuffer(crtc->fb);
/* If not atomic, we can go ahead and pin, and unpin the
* old fb we were passed.
*/