From 573ae4f13f630d6660008f1974c0a8a29c30e18a Mon Sep 17 00:00:00 2001 From: Jens Wiklander 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 Reported-by: Anirban Chakraborty Reported-by: Debdeep Mukhopadhyay Suggested-by: Jerome Forissier Signed-off-by: Jens Wiklander Signed-off-by: Linus Torvalds --- drivers/tee/tee_shm.c | 3 +++ 1 file changed, 3 insertions(+) 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); -- 2.39.5