Bug 210655

Summary: ptrace(2) documentation is incorrect about access checking threads in same thread group
Product: Documentation Reporter: Ted Estes (ted)
Component: man-pagesAssignee: documentation_man-pages (documentation_man-pages)
Status: NEW ---    
Severity: normal CC: alx
Priority: P1    
Hardware: All   
OS: Linux   
URL: https://man7.org/linux/man-pages/man2/ptrace.2.html
Kernel Version: Subsystem:
Regression: No Bisected commit-id:

Description Ted Estes 2020-12-11 23:53:48 UTC
Under "Ptrace access mode checking", the documentation states:
  "1. If the calling thread and the target thread are in the same thread group, access is always allowed."

This is incorrect. A thread may never attach to another in the same group.

Reference, ptrace_attach()
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/kernel/ptrace.c?h=v5.9.14#n380