On Sat, Dec 23, 2017 at 02:26:17AM +0000, Ben Hutchings wrote:

An UNKNOWN_VALUE is not supposed to be derived from a pointer, unless pointer leaks are allowed. Therefore, states_equal() must not treat a state with a pointer in a register as "equal" to a state with an UNKNOWN_VALUE in that register.

This was fixed differently upstream, but the code around here was largely rewritten in 4.14 by commit f1174f77b50c "bpf/verifier: rework value tracking". The bug can be detected by the bpf/verifier sub-test "pointer/scalar confusion in state equality check (way 1)".

Signed-off-by: Ben Hutchings ben@decadent.org.uk Cc: Edward Cree ecree@solarflare.com Cc: Jann Horn jannh@google.com Cc: Alexei Starovoitov ast@kernel.org

Acked-by: Alexei Starovoitov ast@kernel.org