fix(parsing): Handle underflow in A6 parsing by wooffie · Pull Request #23047 · vectordotdev/vector

wooffie · 2025-05-14T12:37:09Z

Summary

Fixed possible panic with integer subtract in dnsmsg-parser. More info in test section.

Change Type

Bug fix
New feature
Non-functional (chore, refactoring, docs)
Performance

Is this a breaking change?

Yes
No

How did you test this PR?

Simple test in lib/dnsmsg-parser/src/dns_message_parser.rs can lead to panic:

#[test]
    fn repro_crash(){
        let raw_dns_message = "oAAAMgABAAAAAAABAAABAAAAACYAAC8BAAAAAaAAAAAAAA==";
        let raw_query_message = BASE64
            .decode(raw_dns_message.as_bytes())
            .expect("Invalid base64 encoded data.");
        let _parse_result = DnsMessageParser::new(raw_query_message).parse_as_query_message();
    }

Panic trace:

 ---- dns_message_parser::tests::repro_crash stdout ----

thread 'dns_message_parser::tests::repro_crash' panicked at lib/dnsmsg-parser/src/dns_message_parser.rs:266:34:
attempt to subtract with overflow
stack backtrace:
   0: rust_begin_unwind
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library/std/src/panicking.rs:692:5
   1: core::panicking::panic_fmt
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library/core/src/panicking.rs:75:14
   2: core::panicking::panic_const::panic_const_sub_overflow
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library/core/src/panicking.rs:178:21
   3: dnsmsg_parser::dns_message_parser::DnsMessageParser::parse_a6_rdata
             at ./src/dns_message_parser.rs:266:34
   4: dnsmsg_parser::dns_message_parser::DnsMessageParser::format_unknown_rdata
             at ./src/dns_message_parser.rs:500:38
   5: dnsmsg_parser::dns_message_parser::DnsMessageParser::parse_dns_record
             at ./src/dns_message_parser.rs:190:47
   6: dnsmsg_parser::dns_message_parser::DnsMessageParser::parse_dns_message_section::{{closure}}
             at ./src/dns_message_parser.rs:184:27
   7: core::iter::adapters::map::map_try_fold::{{closure}}
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/map.rs:95:28
   8: core::iter::traits::iterator::Iterator::try_fold
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs:2370:21
   9: <core::iter::adapters::map::Map<I,F> as core::iter::traits::iterator::Iterator>::try_fold
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/map.rs:121:9
  10: <core::iter::adapters::GenericShunt<I,R> as core::iter::traits::iterator::Iterator>::try_fold
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/mod.rs:191:9
  11: core::iter::traits::iterator::Iterator::try_for_each
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs:2431:9
  12: <core::iter::adapters::GenericShunt<I,R> as core::iter::traits::iterator::Iterator>::next
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/mod.rs:174:14
  13: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter_nested::SpecFromIterNested<T,I>>::from_iter
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/vec/spec_from_iter_nested.rs:25:32
  14: <alloc::vec::Vec<T> as alloc::vec::spec_from_iter::SpecFromIter<T,I>>::from_iter
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/vec/spec_from_iter.rs:34:9
  15: <alloc::vec::Vec<T> as core::iter::traits::collect::FromIterator<T>>::from_iter
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc/src/vec/mod.rs:3427:9
  16: core::iter::traits::iterator::Iterator::collect
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs:1971:9
  17: <core::result::Result<V,E> as core::iter::traits::collect::FromIterator<core::result::Result<A,E>>>::from_iter::{{closure}}
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:1985:51
  18: core::iter::adapters::try_process
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/mod.rs:160:17
  19: <core::result::Result<V,E> as core::iter::traits::collect::FromIterator<core::result::Result<A,E>>>::from_iter
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:1985:9
  20: core::iter::traits::iterator::Iterator::collect
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/traits/iterator.rs:1971:9
  21: dnsmsg_parser::dns_message_parser::DnsMessageParser::parse_dns_message_section
             at ./src/dns_message_parser.rs:182:9
  22: dnsmsg_parser::dns_message_parser::DnsMessageParser::parse_as_query_message
             at ./src/dns_message_parser.rs:119:33
  23: dnsmsg_parser::dns_message_parser::tests::repro_crash
             at ./src/dns_message_parser.rs:1609:29
  24: dnsmsg_parser::dns_message_parser::tests::repro_crash::{{closure}}
             at ./src/dns_message_parser.rs:1604:21
  25: core::ops::function::FnOnce::call_once
             at /home/wooffie/.rustup/toolchains/1.85-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  26: core::ops::function::FnOnce::call_once
             at /rustc/4eb161250e340c8f48f66e2b929ef4a5bed7c181/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Now I just added check like in some places in this source file, maybe this condition can be modified.

Does this PR include user facing changes?

Yes. Please add a changelog fragment based on our guidelines.
No. A maintainer will apply the "no-changelog" label to this PR.

Notes

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Do not hesitate to use @vectordotdev/vector to reach out to us regarding this PR.
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- We recommend adding a pre-push hook, please see this template.
- Alternatively, we recommend running the following locally before pushing to the remote branch:
  - cargo fmt --all
  - cargo clippy --workspace --all-targets -- -D warnings
  - cargo nextest run --workspace (alternatively, you can run cargo test --all)
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After a review is requested, please avoid force pushes to help us review incrementally.
- Feel free to push as many commits as you want. They will be squashed into one before merging.
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References

pront

Thanks @wooffie. Can you add a changelog and the test case you have in the PR description?

fix(parsing): Handle underflow in A6 parsing

001efdc

wooffie requested a review from a team as a code owner May 14, 2025 12:37

pront approved these changes May 14, 2025

View reviewed changes

wooffie added 2 commits May 15, 2025 13:49

Add tests and changelog

5fd674a

Change changelog filename for spelling

aac4eb3

pront enabled auto-merge May 15, 2025 12:55

pront added this pull request to the merge queue May 15, 2025

Merged via the queue into vectordotdev:master with commit ace0dd2 May 15, 2025
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fix(parsing): Handle underflow in A6 parsing#23047

fix(parsing): Handle underflow in A6 parsing#23047
pront merged 3 commits intovectordotdev:masterfrom
wooffie:fix-underflow-dnsparse

wooffie commented May 14, 2025

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wooffie commented May 14, 2025

Summary

Change Type

Is this a breaking change?

How did you test this PR?

Does this PR include user facing changes?

Notes

References

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