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Commit e9d94504 authored by Chema Gonzalez's avatar Chema Gonzalez Committed by David S. Miller
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net: filter: fix length calculation in BPF testsuite



The current probe_filter_length() (the function that calculates the
length of a test BPF filter) behavior is to declare the end of the
filter as soon as it finds {0, *, *, 0}. This is actually a valid
insn ("ld #0"), so any filter with includes "BPF_STMT(BPF_LD | BPF_IMM, 0)"
fails (its length is cut short).

We are changing probe_filter_length() so as to start from the end, and
declare the end of the filter as the first instruction which is not
{0, *, *, 0}. This solution produces a simpler patch than the
alternative of using an explicit end-of-filter mark. It is technically
incorrect if your filter ends up with "ld #0", but that should not
happen anyway.

We also add a new test (LD_IMM_0) that includes ld #0 (does not work
without this patch).

Signed-off-by: default avatarChema Gonzalez <chema@google.com>
Acked-by: default avatarDaniel Borkmann <dborkman@redhat.com>
Acked-by: default avatarAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f7b4e71c
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