CFE-4687: Fixed off-by-one in protocol recv buffers#6177
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ProtocolOpenDir()/ProtocolGet() receive up to CF_MSGSIZE bytes into a char buf[CF_MSGSIZE], but the receive primitives NUL-terminate at buf[received] where received can equal CF_MSGSIZE -- one past the array (TLSRecv/RecvSocketStream both write toget+1 bytes). Drives the real ProtocolOpenDir() over a classic-protocol socketpair with a record-filling reply. Aborts under AddressSanitizer on current code, passes once the buffers are sized CF_BUFSIZE (cfengine#6171). Ref: CFE-4687, cfengine#6171 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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@cf-bottom jenkins please |
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Sure, I triggered a build: Jenkins: https://ci.cfengine.com/job/pr-pipeline/13946/ Packages: http://buildcache.cfengine.com/packages/testing-pr/jenkins-pr-pipeline-13946/ |
olehermanse
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Jun 12, 2026
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At first glance, I'd say it sounds more appropriate that the buffers should be +1 (CF_MSGSIZE + 1) to account for the NUL-byte. However, after reading the comment in your test, I see that CF_BUFSIZE is already used in another place for the same thing (STAT), so it makes some sense to do the same as there.
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ProtocolOpenDir()/ProtocolGet() receive up to CF_MSGSIZE bytes into a char buf[CF_MSGSIZE], but the receive primitives NUL-terminate at buf[received] where received can equal CF_MSGSIZE -- one past the array (TLSRecv/RecvSocketStream both write toget+1 bytes).
Drives the real ProtocolOpenDir() over a classic-protocol socketpair with a record-filling reply. Aborts under AddressSanitizer on current code, passes once the buffers are sized CF_BUFSIZE (#6171).
Ref: CFE-4687, #6171