envoyproxy/envoy

[redis_proxy] potential out of memory/ with untrusted buffer when onData()

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#12,689 opened on Aug 17, 2020

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area/redishelp wanted

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Description

Since documentation of redis_proxy shows it is only accepts trusted data now, I think this is not a security issue, so I post it here.

In the decoder of redis_proxy filter, it reads an integer from the buffer and constructs a vector with size equal to it(pending_integer_.integer_). https://github.com/envoyproxy/envoy/blob/master/source/extensions/filters/network/common/redis/codec_impl.cc#L442

Untrusted buffer containing a very large integer here(as the size of the vector) may lead to out of memory or uncaught length_error exception.

We may consider adding a constraint on the vector length(for example, not more than buffer.size()?) to avoid this bug.

The issue and test case can be found here: https://oss-fuzz.com/testcase-detail/5663259240431616

Contributor guide

Research direction
Examine the decoder in source/extensions/filters/network/common/redis/codec impl.cc around line 442. Add a bounds check on the integer size before constructing the vector to prevent OOM. Ensure the buffer size is not exceeded.
Tech stack
ccpp
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Redis protocol
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75