tee: Fix tee_shm_register() for kernel TEE drivers

Commit 056d3fed3d ("tee: add tee_shm_register_{user,kernel}_buf()")
refactored tee_shm_register() into corresponding user and kernel space
functions named tee_shm_register_{user,kernel}_buf(). The upstream fix
commit 573ae4f13f ("tee: add overflow check in register_shm_helper()")
only applied to tee_shm_register_user_buf().

But the stable kernel 4.19, 5.4, 5.10 and 5.15 don't have the above
mentioned tee_shm_register() refactoring commit. Hence a direct backport
wasn't possible and the fix has to be rather applied to
tee_ioctl_shm_register().

Somehow the fix was correctly backported to 4.19 and 5.4 stable kernels
but the backports for 5.10 and 5.15 stable kernels were broken as fix
was applied to common tee_shm_register() function which broke its kernel
space users such as trusted keys driver.

Fortunately the backport for 5.10 stable kernel was incidently fixed by:
commit 606fe84a4185 ("tee: fix memory leak in tee_shm_register()"). So
fix the backport for 5.15 stable kernel as well.

Fixes: 578c349570d2 ("tee: add overflow check in register_shm_helper()")
Cc: stable@vger.kernel.org # 5.15
Reported-by: Sahil Malhotra <sahil.malhotra@nxp.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tee/tee_core.c

@@ -334,6 +334,9 @@ tee_ioctl_shm_register(struct tee_context *ctx,
 	if (data.flags)
 		return -EINVAL;
 
+	if (!access_ok((void __user *)(unsigned long)data.addr, data.length))
+		return -EFAULT;
+
 	shm = tee_shm_register(ctx, data.addr, data.length,
 			       TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED);
 	if (IS_ERR(shm))

drivers/tee/tee_shm.c

@@ -223,9 +223,6 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 		goto err;
 	}
 
-	if (!access_ok((void __user *)addr, length))
-		return ERR_PTR(-EFAULT);
-
 	mutex_lock(&teedev->mutex);
 	shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
 	mutex_unlock(&teedev->mutex);