[PATCH v2 bpf-next 0/3] bpf: Pointers beyond packet end.

Alexei Starovoitov
2020-11-11T03:12:19Z

From: Alexei Starovoitov <ast@kernel.org>

v1->v2:
- removed set-but-unused variable.
- added Jiri's Tested-by.

In some cases LLVM uses the knowledge that branch is taken to optimze the code
which causes the verifier to reject valid programs.
Teach the verifier to recognize that
r1 = skb->data;
r1 += 10;
r2 = skb->data_end;
if (r1 > r2) {
here r1 points beyond packet_end and subsequent
if (r1 > r2) // always evaluates to "true".
}

Alexei Starovoitov (3):
bpf: Support for pointers beyond pkt_end.
selftests/bpf: Add skb_pkt_end test
selftests/bpf: Add asm tests for pkt vs pkt_end comparison.

include/linux/bpf_verifier.h | 2 +-
kernel/bpf/verifier.c | 129 +++++++++++++++---
.../bpf/prog_tests/test_skb_pkt_end.c | 41 ++++++
.../testing/selftests/bpf/progs/skb_pkt_end.c | 54 ++++++++
.../testing/selftests/bpf/verifier/ctx_skb.c | 42 ++++++
5 files changed, 245 insertions(+), 23 deletions(-)
create mode 100644 tools/testing/selftests/bpf/prog_tests/test_skb_pkt_end.c
create mode 100644 tools/testing/selftests/bpf/progs/skb_pkt_end.c

--
2.24.1