Op 22-08-13 02:10, Ilia Mirkin schreef: > The code expects non-VRAM mem nodes to have a pages list. If that's not > set, it will do a null deref down the line. Warn on that condition and > return an error. > > See https://bugs.freedesktop.org/show_bug.cgi?id=64774 > > Reported-by: Pasi Kärkkäinen <pasik@xxxxxx> > Tested-by: Pasi Kärkkäinen <pasik@xxxxxx> > Signed-off-by: Ilia Mirkin <imirkin@xxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # 3.8+ > --- > > I don't exactly understand what's going on, but this is just a > straightforward way to avoid a null deref that you see happens in the > bug. I haven't figured out the root cause of this, but it's getting > well into the "I have no idea how TTM works" space. However this seems > like a bit of defensive programming -- nouveau_vm_map_sg will pass > node->pages as a list down, which will be dereferenced by > nvc0_vm_map_sg. Perhaps the other arguments should make that > dereferencing not happen, but it definitely was happening here, as you > can see in the bug. > > Ben/Maarten, I'll let you judge whether this check is appropriate, > since like I hope I was able to convey above, I'm just not really sure :) Not it really isn't appropriate.. You'd have to call call nouveau_vm_map_sg_table instead, the only place that doesn't handle that correctly is where it's not expected to be called. Here, have a completely untested patch to fix things... diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -138,17 +143,26 @@ nouveau_user_framebuffer_create(struct drm_device *dev, { struct nouveau_framebuffer *nouveau_fb; struct drm_gem_object *gem; + struct nouveau_bo *nvbo; int ret = -ENOMEM; gem = drm_gem_object_lookup(dev, file_priv, mode_cmd->handles[0]); if (!gem) return ERR_PTR(-ENOENT); + nvbo = nouveau_gem_object(gem); + if (!(nvbo->valid_domains & NOUVEAU_GEM_DOMAIN_VRAM)) { + nv_warn(nouveau_drm(dev), "Trying to create a fb in vram with" + " valid_domains=%08x\n", nvbo->valid_domains); + ret = -EINVAL; + goto err_unref; + } + nouveau_fb = kzalloc(sizeof(struct nouveau_framebuffer), GFP_KERNEL); if (!nouveau_fb) goto err_unref; - ret = nouveau_framebuffer_init(dev, nouveau_fb, mode_cmd, nouveau_gem_object(gem)); + ret = nouveau_framebuffer_init(dev, nouveau_fb, mode_cmd, nvbo); if (ret) goto err; _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
