vxdna: path validation in read_sysfs [SWSPLAT-8844]

[wendyliang25]

Add path validation to read_sysfs().

Code cleanup:

• Use C++ headers (, ) instead of C headers

Testing:

• Add SubmitCcmdReadSysfsPathTraversal unit test covering different paths passed to read_sysfs()

[Copilot]

Pull request overview

This PR implements a security fix to prevent path traversal vulnerabilities in the read_sysfs() function. Malicious guests could previously exploit this by requesting paths like "../../../etc/passwd" to read arbitrary files on the host system.

Key Changes:

• Added path validation using std::filesystem::canonical() to ensure requested paths remain within the device's sysfs root directory
• Migrated from C headers (stdlib.h, string.h) to C++ equivalents (cstdlib, cstring)
• Added comprehensive unit tests covering multiple path traversal attack patterns

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/vxdna/src/vaccel_amdxdna.cpp	Implements path validation logic to prevent directory traversal attacks by canonicalizing and validating paths
src/vxdna/tests/test_vaccel.cpp	Adds security-focused unit test covering various path traversal attack vectors

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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