Commit 748c90c6 authored by Rick Edgecombe's avatar Rick Edgecombe Committed by Dave Hansen
Browse files

x86/shstk: Remove useless clone error handling 



When clone fails after the shadow stack is allocated, any allocated shadow
stack is cleaned up in exit_thread() in copy_process(). So the logic in
copy_thread() is unneeded, and also will not handle failures that happen
outside of copy_thread().

In addition, since there is a second attempt to unmap the same shadow
stack, there is a race where an newly mapped region could get unmapped.

So remove the logic in copy_thread() and rely on exit_thread() to handle
clone failure.

Fixes: b2926a36 ("x86/shstk: Handle thread shadow stack")
Signed-off-by: default avatarRick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Tested-by: default avatarH.J. Lu <hjl.tools@gmail.com>
Link: https://lore.kernel.org/all/20230908203655.543765-3-rick.p.edgecombe%40intel.com
parent 33195560

arch/x86/kernel/process.c

+0 −7
Original line number Diff line number Diff line
@@ -257,13 +257,6 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) 
	if (!ret && unlikely(test_tsk_thread_flag(current, TIF_IO_BITMAP)))

		io_bitmap_share(p);



	/*

	 * If copy_thread() if failing, don't leak the shadow stack possibly

	 * allocated in shstk_alloc_thread_stack() above.

	 */

	if (ret)

		shstk_free(p);



	return ret;

}