From: Steven Price Date: Mon, 19 Dec 2022 14:01:30 +0000 (+0000) Subject: drm/panfrost: Fix GEM handle creation ref-counting X-Git-Tag: v6.1.8~528 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ba3d2c2380e7129b525a787489c0b7e819a3b898;p=platform%2Fkernel%2Flinux-starfive.git drm/panfrost: Fix GEM handle creation ref-counting [ Upstream commit 4217c6ac817451d5116687f3cc6286220dc43d49 ] panfrost_gem_create_with_handle() previously returned a BO but with the only reference being from the handle, which user space could in theory guess and release, causing a use-after-free. Additionally if the call to panfrost_gem_mapping_get() in panfrost_ioctl_create_bo() failed then a(nother) reference on the BO was dropped. The _create_with_handle() is a problematic pattern, so ditch it and instead create the handle in panfrost_ioctl_create_bo(). If the call to panfrost_gem_mapping_get() fails then this means that user space has indeed gone behind our back and freed the handle. In which case just return an error code. Reported-by: Rob Clark Fixes: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver") Signed-off-by: Steven Price Reviewed-by: Rob Clark Link: https://patchwork.freedesktop.org/patch/msgid/20221219140130.410578-1-steven.price@arm.com Signed-off-by: Sasha Levin --- diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c index 2fa5afe..919e6cc 100644 --- a/drivers/gpu/drm/panfrost/panfrost_drv.c +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c @@ -82,6 +82,7 @@ static int panfrost_ioctl_create_bo(struct drm_device *dev, void *data, struct panfrost_gem_object *bo; struct drm_panfrost_create_bo *args = data; struct panfrost_gem_mapping *mapping; + int ret; if (!args->size || args->pad || (args->flags & ~(PANFROST_BO_NOEXEC | PANFROST_BO_HEAP))) @@ -92,21 +93,29 @@ static int panfrost_ioctl_create_bo(struct drm_device *dev, void *data, !(args->flags & PANFROST_BO_NOEXEC)) return -EINVAL; - bo = panfrost_gem_create_with_handle(file, dev, args->size, args->flags, - &args->handle); + bo = panfrost_gem_create(dev, args->size, args->flags); if (IS_ERR(bo)) return PTR_ERR(bo); + ret = drm_gem_handle_create(file, &bo->base.base, &args->handle); + if (ret) + goto out; + mapping = panfrost_gem_mapping_get(bo, priv); - if (!mapping) { - drm_gem_object_put(&bo->base.base); - return -EINVAL; + if (mapping) { + args->offset = mapping->mmnode.start << PAGE_SHIFT; + panfrost_gem_mapping_put(mapping); + } else { + /* This can only happen if the handle from + * drm_gem_handle_create() has already been guessed and freed + * by user space + */ + ret = -EINVAL; } - args->offset = mapping->mmnode.start << PAGE_SHIFT; - panfrost_gem_mapping_put(mapping); - - return 0; +out: + drm_gem_object_put(&bo->base.base); + return ret; } /** diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c index 293e799..3c812fb 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem.c +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c @@ -235,12 +235,8 @@ struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t } struct panfrost_gem_object * -panfrost_gem_create_with_handle(struct drm_file *file_priv, - struct drm_device *dev, size_t size, - u32 flags, - uint32_t *handle) +panfrost_gem_create(struct drm_device *dev, size_t size, u32 flags) { - int ret; struct drm_gem_shmem_object *shmem; struct panfrost_gem_object *bo; @@ -256,16 +252,6 @@ panfrost_gem_create_with_handle(struct drm_file *file_priv, bo->noexec = !!(flags & PANFROST_BO_NOEXEC); bo->is_heap = !!(flags & PANFROST_BO_HEAP); - /* - * Allocate an id of idr table where the obj is registered - * and handle has the id what user can see. - */ - ret = drm_gem_handle_create(file_priv, &shmem->base, handle); - /* drop reference from allocate - handle holds it now. */ - drm_gem_object_put(&shmem->base); - if (ret) - return ERR_PTR(ret); - return bo; } diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h index 8088d5f..ad2877e 100644 --- a/drivers/gpu/drm/panfrost/panfrost_gem.h +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h @@ -69,10 +69,7 @@ panfrost_gem_prime_import_sg_table(struct drm_device *dev, struct sg_table *sgt); struct panfrost_gem_object * -panfrost_gem_create_with_handle(struct drm_file *file_priv, - struct drm_device *dev, size_t size, - u32 flags, - uint32_t *handle); +panfrost_gem_create(struct drm_device *dev, size_t size, u32 flags); int panfrost_gem_open(struct drm_gem_object *obj, struct drm_file *file_priv); void panfrost_gem_close(struct drm_gem_object *obj,