From: Xu Kuohai <xukuohai@xxxxxxxxxx> dst_reg is marked as unknown when BPF_MOD instruction is verified, causing the following bpf prog to be incorrectly rejected. 0: r0 = 0 1: r0 %= 1 // r0 is marked as unknown 2: r1 = 0 3: r1 += 1 4: if r1 < r0 goto pc-2 // verifier concludes the loop is unbounded 5: exit To teach verifier to accept the above prog, this series adds bound tracking for BPF_MOD. v2: - fix build warning reported by kernel test robot <lkp@xxxxxxxxx> [0] - add two more cases and update commit message [0] https://lore.kernel.org/oe-kbuild-all/202303060036.zK05OC5M-lkp@xxxxxxxxx v1: https://lore.kernel.org/bpf/20230306033119.2634976-1-xukuohai@xxxxxxxxxxxxxxx Xu Kuohai (2): bpf: add bound tracking for BPF_MOD selftests/bpf: check if verifier tracks dst_reg bound for BPF_MOD kernel/bpf/verifier.c | 98 ++++++- tools/testing/selftests/bpf/verifier/mod.c | 320 +++++++++++++++++++++ 2 files changed, 413 insertions(+), 5 deletions(-) create mode 100644 tools/testing/selftests/bpf/verifier/mod.c -- 2.30.2
