Re: [uml-devel] problems compiling 2.6.17 against glibc 2.4

[Nix <nix@esperi.org.uk>]

On Mon, 26 Jun 2006, blaisorblade@yahoo.it wrote:
> Ok, I missed one important bit of info. Plus, MARC archives when searching for 
> author don't support restricting to one ML. So, here's the link to the 
> discussion within UML-devel. Which is just a pointer to the issue (he surely 
> doesn't explain here the security issues).

Oh, it was on *l-k*. Right.

The security issue is (probably) that attackers can stick stuff into a
jmp_buf if they can successfully execute arbitrary code in some (buggy)
function, and thus can trigger a later longjmp() by the application
which would go somewhere unexpected. glibc fixes this by xoring the
pointers in the jmp_buf with (IIRC) a TLS-stored random cookie (much as
-fstack-protector sticks a TLS-stored random cookie on the stack;
obviously it can't actually modify the on-stack return address, so that
is the next best thing).

A shame Roland wasn't listening in: he made the original changes and
he's a lot more, well, *helpful* than Ulrich... he'll say what
the problem is where Ulrich will just growl at you.

-- 
`NB: Anyone suggesting that we should say "Tibibytes" instead of
 Terabytes there will be hunted down and brutally slain.
 That is all.' --- Matthew Wilcox

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