This is a note to let you know that I've just added the patch titled tee: add overflow check in register_shm_helper() to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tee-add-overflow-check-in-register_shm_helper.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 573ae4f13f630d6660008f1974c0a8a29c30e18a Mon Sep 17 00:00:00 2001 From: Jens Wiklander <jens.wiklander@xxxxxxxxxx> Date: Thu, 18 Aug 2022 13:08:59 +0200 Subject: tee: add overflow check in register_shm_helper() From: Jens Wiklander <jens.wiklander@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx Reported-by: Nimish Mishra <neelam.nimish@xxxxxxxxx> Reported-by: Anirban Chakraborty <ch.anirban00727@xxxxxxxxx> Reported-by: Debdeep Mukhopadhyay <debdeep.mukhopadhyay@xxxxxxxxx> Suggested-by: Jerome Forissier <jerome.forissier@xxxxxxxxxx> Signed-off-by: Jens Wiklander <jens.wiklander@xxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tee/tee_shm.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -222,6 +222,9 @@ struct tee_shm *tee_shm_register(struct 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); Patches currently in stable-queue which might be from jens.wiklander@xxxxxxxxxx are queue-5.15/tee-add-overflow-check-in-register_shm_helper.patch