From fd485d47437ba1700dd47205a63b9f389a00aa36 Mon Sep 17 00:00:00 2001 From: Jesse Zhang Date: Fri, 9 Oct 2026 18:33:39 +0800 Subject: [PATCH] drm/ttm: return an error when kmapping a BO without pages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ttm_tt objects for imported sg tables (ttm_bo_type_sg, set up by ttm_sg_tt_init() with TTM_TT_FLAG_EXTERNAL) only have DMA addresses and no pages array. ttm_bo_kmap() and ttm_bo_vmap() still dereference ttm->pages for them, so a driver that tries to CPU map such a BO oopses instead of getting an error: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:ttm_bo_kmap+0x26c/0x300 [ttm] Call Trace: amdgpu_bo_kmap+0x89/0xb0 [amdgpu] amdgpu_userq_fence_read_wptr+0x116/0x170 [amdgpu] amdgpu_userq_signal_ioctl+0x3fe/0xbb0 [amdgpu] Return -EINVAL in that case, like ttm_bo_kmap_try_from_panic() already checks for a missing pages array. Fixes: 75a57669cbc8 ("drm/ttm: add ttm_sg_tt_init") Cc: stable@vger.kernel.org Suggested-by: Christian König Reviewed-by: Christian König Signed-off-by: Jesse Zhang Signed-off-by: Arunpravin Paneer Selvam Link: https://patch.msgid.link/20261009103419.4122940-1-Jesse.Zhang@amd.com --- drivers/gpu/drm/ttm/ttm_bo_util.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index bd0b23ac2cc4..f9458a4d5a09 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -356,6 +356,10 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo, if (ret) return ret; + /* Imported sg tables only come with DMA addresses, no pages to map. */ + if (!ttm->pages) + return -EINVAL; + if (num_pages == 1 && ttm->caching == ttm_cached && !(man->use_tt && (ttm->page_flags & TTM_TT_FLAG_DECRYPTED))) { /* @@ -419,7 +423,7 @@ EXPORT_SYMBOL(ttm_bo_kmap_try_from_panic); * * Returns * -ENOMEM: Out of memory. - * -EINVAL: Invalid range. + * -EINVAL: Invalid range or the BO has no pages to map. */ int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page, unsigned long num_pages, @@ -493,7 +497,7 @@ EXPORT_SYMBOL(ttm_bo_kunmap); * * Returns * -ENOMEM: Out of memory. - * -EINVAL: Invalid range. + * -EINVAL: Invalid range or the BO has no pages to map. */ int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map *map) { @@ -537,6 +541,9 @@ int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map *map) if (ret) return ret; + if (!ttm->pages) + return -EINVAL; + /* * We need to use vmap to get the desired page protection * or to make the buffer object look contiguous. -- GitLab