Clamp HTTP3 frame type buf size to reader bytes - #13242
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JosiahWI merged 4 commits intoJun 8, 2026
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The length of the source buffer for HTTP3 type parsing was always taken to be the maximum length of the type field. This seemed to work without UB when I tested it through `Http3FrameDispatcher`, but Kit Chan pointed out that it is risky (apache#11720). This patch refactors the type parsing to guarantee that the number of bytes passed to the parser will not be greater than the number of initialized bytes in the buffer.
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Pull request overview
This PR addresses a fuzzing-reported risk in HTTP/3 frame type parsing by ensuring the type parser never receives a buffer length larger than the number of bytes actually copied from the IOBufferReader, avoiding potential reads of uninitialized stack data.
Changes:
- Clamp the number of bytes used for HTTP/3 frame type parsing to
min(reader.read_avail(), FRAME_TYPE_MAX_BYTES). - Apply the clamping consistently in both
Http3FrameFactory::create()andHttp3FrameFactory::fast_create(). - Add
<algorithm>include to supportstd::min.
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
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[approve ci] |
maskit
approved these changes
Jun 5, 2026
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I'm not sure if it's worth back porting this fix for 10.x. I'd leave it on master for 11.0. |
cmcfarlen
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Jul 29, 2026
* Clamp HTTP3 frame type buf size to reader bytes The length of the source buffer for HTTP3 type parsing was always taken to be the maximum length of the type field. This seemed to work without UB when I tested it through `Http3FrameDispatcher`, but Kit Chan pointed out that it is risky (apache#11720). This patch refactors the type parsing to guarantee that the number of bytes passed to the parser will not be greater than the number of initialized bytes in the buffer. * Fix incorrect identifier name Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> * Fix incorrect identifier * Fix incorrect identifier name Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
cmcfarlen
pushed a commit
to cmcfarlen/trafficserver
that referenced
this pull request
Jul 29, 2026
* Clamp HTTP3 frame type buf size to reader bytes The length of the source buffer for HTTP3 type parsing was always taken to be the maximum length of the type field. This seemed to work without UB when I tested it through `Http3FrameDispatcher`, but Kit Chan pointed out that it is risky (apache#11720). This patch refactors the type parsing to guarantee that the number of bytes passed to the parser will not be greater than the number of initialized bytes in the buffer. * Fix incorrect identifier name Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> * Fix incorrect identifier * Fix incorrect identifier name Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> --------- Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com> (cherry picked from commit 3189423)
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The length of the source buffer for HTTP3 type parsing was always taken
to be the maximum length of the type field. This seemed to work without
UB when I tested it through
Http3FrameDispatcher, but Kit Chan pointedout that it is risky (#11720).
This patch refactors the type parsing to guarantee that the number of
bytes passed to the parser will not be greater than the number of
initialized bytes in the buffer.
Fixes #11720