--- /dev/null
+From 573ae4f13f630d6660008f1974c0a8a29c30e18a Mon Sep 17 00:00:00 2001
+From: Jens Wiklander <jens.wiklander@linaro.org>
+Date: Thu, 18 Aug 2022 13:08:59 +0200
+Subject: tee: add overflow check in register_shm_helper()
+
+From: Jens Wiklander <jens.wiklander@linaro.org>
+
+commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.
+
+With special lengths supplied by user space, register_shm_helper() has
+an integer overflow when calculating the number of pages covered by a
+supplied user space memory region.
+
+This causes internal_get_user_pages_fast() a helper function of
+pin_user_pages_fast() to do a NULL pointer dereference:
+
+ Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
+ Modules linked in:
+ CPU: 1 PID: 173 Comm: optee_example_a Not tainted 5.19.0 #11
+ Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
+ pc : internal_get_user_pages_fast+0x474/0xa80
+ Call trace:
+ internal_get_user_pages_fast+0x474/0xa80
+ pin_user_pages_fast+0x24/0x4c
+ register_shm_helper+0x194/0x330
+ tee_shm_register_user_buf+0x78/0x120
+ tee_ioctl+0xd0/0x11a0
+ __arm64_sys_ioctl+0xa8/0xec
+ invoke_syscall+0x48/0x114
+
+Fix this by adding an an explicit call to access_ok() in
+tee_shm_register_user_buf() to catch an invalid user space address
+early.
+
+Fixes: 033ddf12bcf5 ("tee: add register user memory")
+Cc: stable@vger.kernel.org
+Reported-by: Nimish Mishra <neelam.nimish@gmail.com>
+Reported-by: Anirban Chakraborty <ch.anirban00727@gmail.com>
+Reported-by: Debdeep Mukhopadhyay <debdeep.mukhopadhyay@gmail.com>
+Suggested-by: Jerome Forissier <jerome.forissier@linaro.org>
+Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+[JW: backport to stable-4.19 + update commit message]
+Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/tee/tee_core.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+--- a/drivers/tee/tee_core.c
++++ b/drivers/tee/tee_core.c
+@@ -175,6 +175,10 @@ tee_ioctl_shm_register(struct tee_contex
+ if (data.flags)
+ return -EINVAL;
+
++ if (!access_ok(VERIFY_WRITE, (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))