Re: [PATCH v2] fork: initialize function graph state before copy_exec_state()

On 2026-08-22 17:22, Steven Rostedt wrote:
> On Sat, 22 Aug 2026 08:49:27 +0000
> Jérémy Jean <[email protected]> wrote:
> 
>> dup_task_struct() copies the parent's task_struct, including 
>> ret_stack.
>> ftrace_graph_init_task() clears the copied function graph state, but 
>> it
>> currently runs after copy_exec_state().
>> 
>> For non-CLONE_VM forks, copy_exec_state() allocates a new 
>> task_exec_state.
>> If that allocation fails, copy_process() reaches bad_fork_free and
>> free_task() calls ftrace_graph_exit_task(). Since the child still 
>> carries
>> the parent's ret_stack pointer, the unwind frees the parent's active
>> function graph return stack. The parent subsequently accesses freed 
>> memory
>> from function_graph_enter_regs().
>> 
> 
> As this effects function_graph tracing, please resend and Cc:
> [email protected] so that it gets to the proper
> patchwork. It will need to go through my tree so that it gets the
> proper testing.

Hello Steve,

Done. Thanks for the feedback.
Let me know if I can help more.

Regards,
Jérémy