[BUG] ioctl TCGETS return and glibc throws "**** stack smashing detected ***"

[jessehui]

Describe the bug

In the make test, when running ioctl test with glibc, the test will fail with error message: **** stack smashing detected ***.

To reproduce

Steps to reproduce the behavior:

1. make
2. comment the SGX related tests in "ioctl" test case
3. TESTS=ioctl make test-glibc

Expected behavior

make test-glibc should succeed.

Environment

• HW: [e.g. SGX1, SGX2] SGX2
• OS: [e.g. Ubuntu18.04, CentOS8.1] ubuntu
• Occlum version: [e.g. 0.17.0] NGO master

Additional context

After some digging, I found that it is related with isatty function which will call INTERNAL_SYSCALL macro in glibc and finally call ioctl syscall with TCGETS. However, I have inspected the implementation of TCGETS and didn't find anything abnormal.

There are actually two ways to workaround that I have tried:
(1) Directly use syscall to replace INTERNAL_SYSCALL macro
(2) Shrink the size of TCGETS related struct (from 32 to 30)

However, in CI environment, this error will not show. The reason is unclear.

Possible solution/Implementation

In my opinion, this could be related to syscall entry or the memory manipulation in ioctl implementation but I am not sure.