CODEWITHSUNDEEP
linuxlinux-kernelsystem-calls
LKL
LKL

Reputation: 234

Clone() system call in linux

What happens when I call clone system call by passing 0 as the stack_start? According to manual pages on clone it should return -EINVAL, but when I do that, it is showing SIGSEGV (11) error.

clone(func,NULL,0,args);

should return -EINVAL, but its failing with SIGSEGV

Upvotes: 2

Views: 1705

Answers (1)

Ilya Matveychikov
Ilya Matveychikov

Reputation: 4024

According to linux kernel there is such a call chain:

sys_clone(...stack_start...) -> do_fork

do_fork(...stack_start...) -> copy_process

copy_process(...stack_start...) -> copy_thread

copy_thread(...stack_start...) on X86_32 OR copy_thread(...stack_start...) on X86_64

Looking at the copy_thread leads me to assumption that as this function doesn't check for stack_start correctness (sp argument in code) so after cloning we have a task with invalid stack pointer and first reference at zero address leads to SIGSEGV.

I'll suggest you to look at the glibc wrapper for clone function also.

Upvotes: 1

Related Questions