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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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