[PATCH] ARM: Add SWP/SWPB emulation for ARMv7 processors (v2)

Leif Lindholm Leif.Lindholm at arm.com
Mon Jan 4 13:18:55 EST 2010

> From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
> Sent: 19 December 2009 17:29

> > I wonder if there could be an exploit with Leif's current
> > implementation. The LDREX/STREX pair to uncached or device memory may
> > never complete. This way a user SWP to something like the frame
> > buffer would lock the kernel.
> That means we shouldn't consider applying it until that has been
> investigated.

What if I modify the patch such that a failed STREX causes the emulation to
return success without readjusting the PC? This would result in the SWP
instruction being executed again upon returning to the application - removing
the potential kernel lockup.


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