Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 6 Dec 2017 10:31:15 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'David Miller' <davem@...emloft.net>, "geert@...ux-m68k.org"
	<geert@...ux-m68k.org>
CC: "me@...in.cc" <me@...in.cc>, "kernel-hardening@...ts.openwall.com"
	<kernel-hardening@...ts.openwall.com>, "torvalds@...ux-foundation.org"
	<torvalds@...ux-foundation.org>, "Jason@...c4.com" <Jason@...c4.com>,
	"tytso@....edu" <tytso@....edu>, "keescook@...omium.org"
	<keescook@...omium.org>, "pbonzini@...hat.com" <pbonzini@...hat.com>,
	"tycho@...ho.ws" <tycho@...ho.ws>, "william.c.roberts@...el.com"
	<william.c.roberts@...el.com>, "tj@...nel.org" <tj@...nel.org>,
	"Golden_Miller83@...tonmail.ch" <Golden_Miller83@...tonmail.ch>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>, "pmladek@...e.com"
	<pmladek@...e.com>, "joe@...ches.com" <joe@...ches.com>, "ijc@...lion.org.uk"
	<ijc@...lion.org.uk>, "sergey.senozhatsky@...il.com"
	<sergey.senozhatsky@...il.com>, "catalin.marinas@....com"
	<catalin.marinas@....com>, "wilal.deacon@....com" <wilal.deacon@....com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>, "cfries@...gle.com"
	<cfries@...gle.com>, "olorin@...gle.com" <olorin@...gle.com>,
	"danielmicay@...il.com" <danielmicay@...il.com>, "tixxdz@...il.com"
	<tixxdz@...il.com>, "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>, "sfr@...b.auug.org.au"
	<sfr@...b.auug.org.au>, "aryabinin@...tuozzo.com" <aryabinin@...tuozzo.com>,
	"glider@...gle.com" <glider@...gle.com>, "dvyukov@...gle.com"
	<dvyukov@...gle.com>, "akpm@...ux-foundation.org"
	<akpm@...ux-foundation.org>, "sergei.shtylyov@...entembedded.com"
	<sergei.shtylyov@...entembedded.com>
Subject: RE: [PATCH V11 3/5] printk: hash addresses printed with %p

From: David Miller
> Sent: 05 December 2017 20:31
...
> > Would it make sense to keep the 3 lowest bits of the address?
> >
> > Currently printed pointers no longer have any correlation with the actual
> > alignment in memory of the object, which is a typical cause of a class of bugs.
> 
> Yeah, this is driving people nuts who wonder why pointers are aligned
> all weird now.

I can also image issues where you want to know whether 2 pointers point
into the same structure (like an skb).
Useful if you suspect that code is using a stale pointer because the
skb got reallocated by some internal function.
I'm not sure such pointers are printed by default though.

I know I have debugged things that required hexdumps of memory areas
referenced by traced pointers.
I won't have done that for anything written with the kernel printf because
getting any more info for a linux kernel oops is actually quite hard.

	David

Powered by blists - more mailing lists

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.