[bpf,v2,0/2] bpf: fix accesses to uninit stack slots

Message

Andrei Matei Nov. 26, 2023, 1:50 a.m. UTC

Fix two related issues issues around verifying stack accesses:
1. accesses to uninitialized stack memory was allowed inconsistently
2. the maximum stack depth needed for a program was not always
maintained correctly

The two issues are fixed together in one commit because the code for one
affects the other.

The second patch is tests only. It was split for review purposes; it can
be squashed when merging if it looks good.

Andrei Matei (2):
  bpf: fix accesses to uninit stack slots
  bpf: new verifier tests for stack access

 include/linux/bpf_verifier.h                  |  4 ++
 kernel/bpf/verifier.c                         | 70 ++++++++-----------
 .../selftests/bpf/progs/test_global_func16.c  |  2 +-
 .../bpf/progs/verifier_basic_stack.c          |  6 +-
 .../selftests/bpf/progs/verifier_int_ptr.c    |  2 +-
 .../selftests/bpf/progs/verifier_raw_stack.c  |  2 +-
 .../selftests/bpf/progs/verifier_var_off.c    |  4 +-
 tools/testing/selftests/bpf/test_verifier.c   | 24 +++++++
 .../selftests/bpf/verifier/atomic_cmpxchg.c   | 11 ---
 tools/testing/selftests/bpf/verifier/calls.c  |  2 +-
 tools/testing/selftests/bpf/verifier/stack.c  | 40 +++++++++++
 11 files changed, 106 insertions(+), 61 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/verifier/stack.c