drm/msm/gem: Add check for kmalloc

Add the check for the return value of kmalloc in order to avoid
NULL pointer dereference in copy_from_user.

Fixes: 20224d71 ("drm/msm/submit: Move copy_from_user ahead of locking bos")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/514678/
Link: https://lore.kernel.org/r/20221212091117.43511-1-jiasheng@iscas.ac.cnSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -209,6 +209,10 @@ static int submit_lookup_cmds(struct msm_gem_submit *submit,
 			goto out;
 		}
 		submit->cmd[i].relocs = kmalloc(sz, GFP_KERNEL);
+		if (!submit->cmd[i].relocs) {
+			ret = -ENOMEM;
+			goto out;
+		}
 		ret = copy_from_user(submit->cmd[i].relocs, userptr, sz);
 		if (ret) {
 			ret = -EFAULT;