From fa4a24f5b30dcefc7dff4352deb97b061a7591e2 Mon Sep 17 00:00:00 2001 From: Tomi Valkeinen Date: Tue, 6 Aug 2024 16:50:29 +0300 Subject: [PATCH] drm/omap: Fix locking in omap_gem_new_dmabuf() [ Upstream commit e6a1c4037227539373c8cf484ace83833e2ad6a2 ] omap_gem_new_dmabuf() creates the new gem object, and then takes and holds the omap_obj->lock for the rest of the function. This has two issues: - omap_gem_free_object(), which is called in the error paths, also takes the same lock, leading to deadlock - Even if the above wouldn't happen, in the error cases omap_gem_new_dmabuf() still unlocks omap_obj->lock, even after the omap_obj has already been freed. Furthermore, I don't think there's any reason to take the lock at all, as the object was just created and not yet shared with anyone else. To fix all this, drop taking the lock. Fixes: 3cbd0c587b12 ("drm/omap: gem: Replace struct_mutex usage with omap_obj private lock") Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/511b99d7-aade-4f92-bd3e-63163a13d617@stanley.mountain/ Reviewed-by: Sebastian Reichel Signed-off-by: Tomi Valkeinen Link: https://patchwork.freedesktop.org/patch/msgid/20240806-omapdrm-misc-fixes-v1-3-15d31aea0831@ideasonboard.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/omapdrm/omap_gem.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c index cf571796fd26..8fdb12ce2f88 100644 --- a/drivers/gpu/drm/omapdrm/omap_gem.c +++ b/drivers/gpu/drm/omapdrm/omap_gem.c @@ -1408,8 +1408,6 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size, omap_obj = to_omap_bo(obj); - mutex_lock(&omap_obj->lock); - omap_obj->sgt = sgt; if (sgt->orig_nents == 1) { @@ -1424,21 +1422,17 @@ struct drm_gem_object *omap_gem_new_dmabuf(struct drm_device *dev, size_t size, pages = kcalloc(npages, sizeof(*pages), GFP_KERNEL); if (!pages) { omap_gem_free_object(obj); - obj = ERR_PTR(-ENOMEM); - goto done; + return ERR_PTR(-ENOMEM); } omap_obj->pages = pages; ret = drm_prime_sg_to_page_array(sgt, pages, npages); if (ret) { omap_gem_free_object(obj); - obj = ERR_PTR(-ENOMEM); - goto done; + return ERR_PTR(-ENOMEM); } } -done: - mutex_unlock(&omap_obj->lock); return obj; }