This is a note to let you know that I've just added the patch titled
drm/omap: Fix locking in omap_gem_new_dmabuf()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-omap-fix-locking-in-omap_gem_new_dmabuf.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e6803617d91fedadce8fb8c5d2f89161f8009688
Author: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Date: Tue Aug 6 16:50:29 2024 +0300
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 <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/all/511b99d7-aade-4f92-bd3e-63163a13d617@stanley.mountain/
Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240806-omapdrm-misc-fixes-v1-3-15d31aea0831@xxxxxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 38af6195d9593..ed206312ab426 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -1303,8 +1303,6 @@ 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) {
@@ -1319,21 +1317,17 @@ 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;
}
