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Wipe channel strings that can carry secrets - #1358
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ejohnstown wants to merge 2 commits into
Open
ejohnstown wants to merge 2 commits into
ejohnstown wants to merge 2 commits into
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The env branch decodes the peer's variable value into a stack buffer that can carry a token. Zero it before it leaves scope, on success and on a parse error alike. Issue: F-8849
The client keeps its exec command line, which can carry credentials, in ssh->channelName. FreeChannelName() wipes and frees it, mirroring FreeChannelCommand() on the server side. - use it in SshResourceFree() and at the three wolfSSH_SetChannelType() release sites - unit test reads back each freed name through a retaining allocator Issue: F-14691
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🟢 Approval recommended
No active review issues remain for the changes intended to reduce credential remnants in memory.
No open issues 🎉
What changed in this PR
This PR reduces credential remnants in memory by wiping channel strings before release in wolfSSH’s request handling and client session cleanup.
Changes:
- Wipes the temporary environment-request value before leaving its handling block.
- Centralizes wiping and freeing stored exec/subsystem names in
FreeChannelName(). - Adds unit coverage that checks released exec-name buffers after channel-type changes, command replacement, and session cleanup.
| File | Description |
|---|---|
wolfssh/internal.h |
Declares the shared FreeChannelName() helper. |
tests/unit.c |
Adds and registers exec-name wiping tests. |
src/ssh.c |
Uses the cleanup helper when replacing or dropping channel names. |
src/internal.c |
Implements channel-name wiping, integrates session cleanup, and wipes environment-request values. |
Review effort: Balanced
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Fenrir Automated Review — PR #1358
Scan targets checked: wolfssh-src, wolfssh-bugs
Coverage: 3 of 4 in-scope changed file(s) opened by the reviewer; not opened: wolfssh/internal.h
Fenrir result: Approved ✅
No new issues found in the changed files.
Advisory only — this automated result does not count as a GitHub approval.
Review tier: Lite
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Two channel strings that can hold credentials are zeroed before they
are released.
unit test reads back each freed name
Issue: F-8849, F-14691