Frederic Lecaille 8f6cb8f452 BUG/MINOR: qpack: fix 62-bit overflow and 1-byte OOB reads in decoding
This patch improves the robustness of the QPACK varint decoder and fixes
potential 1-byte out-of-bounds reads in qpack_decode_fs().

In qpack_decode_fs(), two 1-byte OOB reads were possible on truncated
streams between two varint decoding. These occurred when trying to read
the byte containing the Huffman bit <h> and the Value Length prefix
immediately following an Index or a Name Length.

Note that these OOB are limited to a single byte because
qpack_get_varint() already ensures that its input length is non-zero
before consuming any data.

The fixes in qpack_decode_fs() are:
- When decoding an index, we now verify that at least one byte remains
  to safely access the following <h> bit and value length.
- When decoding a literal, we now check len < name_len + 1 to ensure
  the byte starting the header value is reachable.

In qpack_get_varint(), the maximum value is now strictly capped at 2^62-1
as per RFC. This is enforced using a budget-based check:

   (v & 127) > (limit - ret) >> shift

This prevents values from  overflowing into the 63rd or 64th bits, which
would otherwise break subsequent signed comparisons (e.g., if (len < name_len))
by interpreting the length as a negative value, leading to false positive
tests.

Thank you to @jming912 for having reported this issue in GH #3302.

Must be backported as far as 2.6
2026-03-20 19:40:11 +01:00
2026-03-20 10:14:59 +01:00
2026-03-20 10:14:59 +01:00
2026-03-20 10:14:59 +01:00

HAProxy

alpine/musl AWS-LC Illumos NetBSD FreeBSD VTest

HAProxy logo

HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

Installation

The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.

Getting help

The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.

The issue tracker is only for bug reports or feature requests.

Documentation

The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.

Please refer to the following files depending on what you're looking for:

  • INSTALL for instructions on how to build and install HAProxy
  • BRANCHES to understand the project's life cycle and what version to use
  • LICENSE for the project's license
  • CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory:

License

HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.

Description
No description provided
Readme 176 MiB
Languages
C 98.1%
Shell 0.9%
Makefile 0.5%
Lua 0.2%
Python 0.1%