On Thu, May 21, 2020 at 1:07 PM John Fastabend <john.fastabend@xxxxxxxxx> wrote: > > This series adds logic to the verifier to handle the case where a > pointer is known to be non-null but then the verifier encountesr a > instruction, such as 'if ptr == 0 goto X' or 'if ptr != 0 goto X', > where the pointer is compared against 0. Because the verifier tracks > if a pointer may be null in many cases we can improve the branch > tracking by following the case known to be true. > > The first patch adds the verifier logic and patches 2-4 add the > test cases. > > v1->v2: fix verifier logic to return -1 indicating both paths must > still be walked if value is not zero. Move mark_precision skip for > this case into caller of mark_precision to ensure mark_precision can > still catch other misuses. And add PTR_TYPE_BTF_ID to our list of > supported types. Finally add one more test to catch the value not > equal zero case. Thanks to Andrii for original review. > > Also fixed up commit messages hopefully its better now. > Yeah, much better, thanks! Few typos don't count ;) For the series: Acked-by: Andrii Nakryiko <andriin@xxxxxx> > --- > > John Fastabend (4): > bpf: verifier track null pointer branch_taken with JNE and JEQ > bpf: selftests, verifier case for non null pointer check branch taken > bpf: selftests, verifier case for non null pointer map value branch > bpf: selftests, add printk to test_sk_lookup_kern to encode null ptr check > > > kernel/bpf/verifier.c | 36 ++++++++++++++++++-- > .../selftests/bpf/progs/test_sk_lookup_kern.c | 1 + > .../testing/selftests/bpf/verifier/ref_tracking.c | 33 ++++++++++++++++++ > .../testing/selftests/bpf/verifier/value_or_null.c | 19 +++++++++++ > 4 files changed, 86 insertions(+), 3 deletions(-) > > -- > Signature
