[bpf,v3,0/3] bpf: fix accesses to uninit stack slots

Message

Andrei Matei Dec. 2, 2023, 11:05 p.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.

V2 to V3:
- address review comments from Andrii and Eduard
- drop new verifier tests in favor of editing existing tests to check
  for stack depth
- append a patch with a bit of cleanup coming out of the previous review

Andrei Matei (3):
  bpf: add some comments to stack representation
  bpf: fix accesses to uninit stack slots
  bpf: minor cleanup around stack bounds

 include/linux/bpf_verifier.h                  | 14 ++++
 kernel/bpf/verifier.c                         | 73 +++++++++----------
 tools/testing/selftests/bpf/progs/iters.c     |  2 +-
 .../selftests/bpf/progs/test_global_func16.c  |  2 +-
 .../bpf/progs/verifier_basic_stack.c          |  8 +-
 .../selftests/bpf/progs/verifier_int_ptr.c    |  5 +-
 .../selftests/bpf/progs/verifier_raw_stack.c  |  5 +-
 .../selftests/bpf/progs/verifier_var_off.c    | 62 +++++++++++++---
 .../selftests/bpf/verifier/atomic_cmpxchg.c   | 11 ---
 tools/testing/selftests/bpf/verifier/calls.c  |  4 +-
 10 files changed, 113 insertions(+), 73 deletions(-)