Re: [PATCH] insane: detect and warn about relocations in .text

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Wed, 2012-10-03 at 11:44 +0100, Phil Blundell wrote:
> On Wed, 2012-10-03 at 12:31 +0200, Martin Jansa wrote:
> > On Wed, Oct 03, 2012 at 11:24:12AM +0100, Phil Blundell wrote:
> > > Signed-off-by: Phil Blundell <pb@pbcl.net>
> > 
> > Can you add a bit longer description of possible issues with relocations
> > in .text? So that people seeing this issue will know how dangerous it is
> > for them?
> > 
> > From my understanding (after reading
> > http://www.gentoo.org/proj/en/hardened/pic-fix-guide.xml) it's mostly
> > performance issue?
> 
> Yes, that's correct.  It basically falls into the same sort of category
> as useless-rpaths; the binary will still work, but there will be some
> adverse impact on performance and memory usage.  
> 
> Historically, the most common cause of DT_TEXTREL was accidentally
> linking non-PIC code into a DSO.  Recent versions of the linker will
> flatly refuse to do this on at least some architectures, though, so
> hopefully this problem will just go away over time.

Am I right in thinking this is also a marginal help to 'security' since
if the .text segment is loaded read only, it becomes slightly harder for
certain kinds of overflow attacks to work?

Cheers,

Richard