Messages in this thread | | | Date | Tue, 01 Jun 2021 19:21:27 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [RFC PATCH 2/6] powerpc/trace: Add support for stack tracer |
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Naveen N. Rao wrote: > + > +unsigned long ftrace_get_traced_func_if_no_stackframe(unsigned long ip, unsigned long *stack) > +{ > + if (!is_ftrace_entry(ip)) > + return 0; > + > + if (IS_ENABLED(CONFIG_PPC32)) > + return stack[11]; /* see MCOUNT_SAVE_FRAME */ > + > + if (!IS_ENABLED(CONFIG_MPROFILE_KERNEL)) > + return 0; > + > + return stack[(STACK_FRAME_OVERHEAD + offsetof(struct pt_regs, nip)) / sizeof(unsigned long)];
Looking at Daniel's patch to address KASAN errors with our stack walk code in show_stack() [*], I realized that I am not validating the stack pointer here for the above accesses...
[*] http://lkml.kernel.org/r/20210528074806.1311297-1-dja@axtens.net
> +} > + > +#ifdef CONFIG_STACK_TRACER > +void stack_get_trace(unsigned long traced_ip, > + unsigned long *stack_ref __maybe_unused, > + unsigned long stack_size __maybe_unused, > + int *tracer_frame) > +{ > + unsigned long sp, newsp, top, ip; > + int ftrace_call_found = 0; > + unsigned long *stack; > + int i = 0; > + > + sp = current_stack_frame(); > + top = (unsigned long)task_stack_page(current) + THREAD_SIZE; > + > + while (validate_sp(sp, current, STACK_FRAME_OVERHEAD) && i < STACK_TRACE_ENTRIES) { > + stack = (unsigned long *) sp; > + newsp = stack[0]; > + ip = stack[STACK_FRAME_LR_SAVE]; > + > + if (ftrace_call_found) { > + stack_dump_trace[i] = ip; > + stack_trace_index[i++] = top - sp; > + }
And I need to make the above accesses bypass KASAN as well.
- Naveen
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