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Date:   Thu, 9 Nov 2017 13:23:18 +0900
From:   Sergey Senozhatsky <>
To:     Steven Rostedt <>
Cc:     "Tobin C. Harding" <>,,
        "Jason A. Donenfeld" <>,
        Theodore Ts'o <>,
        Linus Torvalds <>,
        Kees Cook <>,
        Paolo Bonzini <>,
        Tycho Andersen <>,
        "Roberts, William C" <>,
        Tejun Heo <>,
        Jordan Glover <>,
        Greg KH <>,
        Petr Mladek <>, Joe Perches <>,
        Ian Campbell <>,
        Sergey Senozhatsky <>,
        Catalin Marinas <>,
        Will Deacon <>,
        Chris Fries <>,
        Dave Weinstein <>,
        Daniel Micay <>,
        Djalal Harouni <>,
        "Paul E. McKenney" <>,
        Andy Lutomirski <>,
        Peter Zijlstra <>,
        David Miller <>,
        Network Development <>,
Subject: Re: [PATCH] kallsyms: don't leak address when printing symbol

On (11/08/17 22:35), Steven Rostedt wrote:
> On Thu,  9 Nov 2017 12:50:29 +1100
> "Tobin C. Harding" <> wrote:
> > Currently if a pointer is printed using %p[ssB] and the symbol is not
> > found (kallsyms_lookup() fails) then we print the actual address. This
> > leaks kernel addresses. We should instead print something _safe_.
> > 
> > Print "<no-symbol>" instead of kernel address.
> Ug, ftrace requires this to work as is, as it uses it to print some
> addresses that may or may not be a symbol.
> If anything, can this return a success or failure if it were to find a
> symbol or not, and then something like ftrace could decide to use %x if
> it does not.
> And yes, ftrace leaks kernel addresses all over the place, that's just
> the nature of tracing the kernel.

agree, I kinda suspect that that "0x%lx" sometimes can be useful.
at least one can tell if the frame is from modules or kernel, and
objdump it may be.


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