bpf/verifier: Fix states_equal() comparison of pointer and UNKNOWN

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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 f1174f77b5 "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>
Cc: Daniel Borkmann <daniel@iogearbox.net>

...

This commit is contained in:

Ben Hutchings 2017-12-23 02:26:17 +00:00 • committed by Greg Kroah-Hartman

parent 69cf72b287

commit 37435f7e80

1 changed files with 3 additions and 2 deletions

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kernel/bpf/verifier.c

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