Date: Thu, 9 Nov 2017 13:23:18 +0900 From: Sergey Senozhatsky <sergey.senozhatsky.work@...il.com> To: Steven Rostedt <rostedt@...dmis.org> Cc: "Tobin C. Harding" <me@...in.cc>, kernel-hardening@...ts.openwall.com, "Jason A. Donenfeld" <Jason@...c4.com>, Theodore Ts'o <tytso@....edu>, Linus Torvalds <torvalds@...ux-foundation.org>, Kees Cook <keescook@...omium.org>, Paolo Bonzini <pbonzini@...hat.com>, Tycho Andersen <tycho@...ker.com>, "Roberts, William C" <william.c.roberts@...el.com>, Tejun Heo <tj@...nel.org>, Jordan Glover <Golden_Miller83@...tonmail.ch>, Greg KH <gregkh@...uxfoundation.org>, Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>, Ian Campbell <ijc@...lion.org.uk>, Sergey Senozhatsky <sergey.senozhatsky@...il.com>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <wil.deacon@....com>, Chris Fries <cfries@...gle.com>, Dave Weinstein <olorin@...gle.com>, Daniel Micay <danielmicay@...il.com>, Djalal Harouni <tixxdz@...il.com>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>, David Miller <davem@...emloft.net>, Network Development <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org 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" <me@...in.cc> 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. -ss
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