The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

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: [PATCH] tee: add overflow check in register_shm_helper()

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

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c index f2b1bcefcadd..1175f3a46859 100644 --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -326,6 +326,9 @@ struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx, void *ret; int id;

+ if (!access_ok((void __user *)addr, length)) + return ERR_PTR(-EFAULT); + mutex_lock(&teedev->mutex); id = idr_alloc(&teedev->idr, NULL, 1, 0, GFP_KERNEL); mutex_unlock(&teedev->mutex);