On 24/03/2025 22:29, Maíra Canal wrote:
Hi Tvrtko,
On 18/03/25 12:54, Tvrtko Ursulin wrote:
Drm_syncobj_array_find() helper is used from many userspace ioctl entry
points with the task of looking up userspace handles to internal objects.
We can easily avoid one temporary allocation by making it read the
handles
as it is looking them up.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
---
drivers/gpu/drm/drm_syncobj.c | 44 +++++++++++++++++------------------
1 file changed, 21 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/
drm_syncobj.c
index fd5ba6c89666..cdda2df06bec 100644
--- a/drivers/gpu/drm/drm_syncobj.c
+++ b/drivers/gpu/drm/drm_syncobj.c
@@ -1213,48 +1213,46 @@ signed long drm_timeout_abs_to_jiffies(int64_t
timeout_nsec)
EXPORT_SYMBOL(drm_timeout_abs_to_jiffies);
static int drm_syncobj_array_find(struct drm_file *file_private,
- void __user *user_handles,
- uint32_t count_handles,
+ u32 __user *handles,
+ uint32_t count,
struct drm_syncobj ***syncobjs_out)
{
- uint32_t i, *handles;
struct drm_syncobj **syncobjs;
+ uint32_t i;
int ret;
- handles = kmalloc_array(count_handles, sizeof(*handles),
GFP_KERNEL);
- if (handles == NULL)
+ if (!access_ok(handles, count * sizeof(*handles)))
+ return -EFAULT;
+
+ syncobjs = kmalloc_array(count, sizeof(*syncobjs), GFP_KERNEL);
+ if (!syncobjs)
return -ENOMEM;
- if (copy_from_user(handles, user_handles,
- sizeof(uint32_t) * count_handles)) {
- ret = -EFAULT;
- goto err_free_handles;
- }
+ for (i = 0; i < count; i++) {
+ u64 handle;
I believe this is a u32.
Well spotted.
- syncobjs = kmalloc_array(count_handles, sizeof(*syncobjs),
GFP_KERNEL);
- if (syncobjs == NULL) {
- ret = -ENOMEM;
- goto err_free_handles;
- }
-
- for (i = 0; i < count_handles; i++) {
- syncobjs[i] = drm_syncobj_find(file_private, handles[i]);
+ if (__get_user(handle, handles++)) {
+ ret = -EFAULT;
+ syncobjs[i] = NULL;
Do we need to assign syncobjs[i] to NULL? Can we just go to
err_put_syncobjs?
+ goto err_put_syncobjs;
+ }
+ syncobjs[i] = drm_syncobj_find(file_private, handle);
if (!syncobjs[i]) {
ret = -ENOENT;
goto err_put_syncobjs;
}
}
- kfree(handles);
*syncobjs_out = syncobjs;
return 0;
err_put_syncobjs:
- while (i-- > 0)
- drm_syncobj_put(syncobjs[i]);
+ while (i > 0) {
+ if (syncobjs[i])
I'm not sure if I understand which scenario this would be needed. For
the first syncobj that we don't find, we go to err_free_handles and
AFAIU all previous syncobjs exist, so there wouldn't be a need to check
if the syncobj != NULL.
Well spotted again. I don't remember why I thought I needed to change
this since it looks the old unwind works fine with added __get_user
failure path.
Regards,
Tvrtko
+ drm_syncobj_put(syncobjs[i]);
+ i--;
+ }
kfree(syncobjs);
-err_free_handles:
- kfree(handles);
return ret;
}
