linux-kernel - [PATCH 0/9] Series to make copy_from_user to a stack slot provable right

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Date:	Sat, 26 Sep 2009 20:49:51 +0200
From:	Arjan van de Ven <arjan@...radead.org>
To:	linux-kernel@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, mingo@...e.hu
Subject: [PATCH 0/9] Series to make copy_from_user to a stack slot provable
 right

[PATCH 0/9] Series to make copy_from_user to a stack slot provable right

This series contains a series of patches that, when applied, make every
copy_from_user() in a make allyesconfig to a (direct) stack slot
provable-by-gcc to have a correct size.

This is useful because if we fix all of these, we can make the non-provable
case an error, as an indication of a possible security hole.

Now the series has 4 types of patches
1) changes where the original code really was missing checks
2) changes where the checks were coded so complex and games were played with
   types, that I (and the compiler) couldn't be sure if it was correct or
   not
3) changes where we're hitting a small gcc missing optimization, but where
   a simplification of the code allows gcc to prove things anyway.
   (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41477 is filed for this)
4) a case in sys_socketcall where Dave Miller and co were very smart in
   optimizing the code to the point where it's not reasonable for gcc
   to realize the result is ok.

-- 
Arjan van de Ven 	Intel Open Source Technology Centre
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