On 3/2/2021 5:30 AM, Daniel P. Berrangé wrote:
On Mon, Mar 01, 2021 at 03:39:42PM -0500, Daniele Buono wrote:
Hi Daniel,
On 3/1/2021 10:08 AM, Daniel P. Berrangé wrote:
What are the unique failure scenarios for CFI that these jobs are
likely to expose ? Is it likely that we'll have cases where
CFI succeeds in say, x86_64 target, but fails in aarch64 target ?
For CFI to fail (even if it shouldn't) you'll need code that is calling a
function pointer that was not well defined at compile time. Although
unlikely, that could happen everywhere in the code.
What does "was not well defined" mean here ?
At high level, the compiler creates metadata for every function. Before
jumping to a function pointer, it makes sure that the pointer and the
pointee have matching types.
Not well defined means one of these two cases:
1. The function has a different type than the pointer -> Most likely an
error
2. The function was not available at compile time so the compiler could
not create the related metadata -> Most likely a false positive.
Thanks,
Daniele
