fix: add buffer-length check in imgfb.c

[anupamme]

Summary

Fix critical severity security issue in gpu/imgfb/imgfb.c.

Vulnerability

Field	Value
ID	V-001
Severity	CRITICAL
Scanner	multi_agent_ai
Rule	V-001
File	gpu/imgfb/imgfb.c:143
Assessment	Likely exploitable
CWE	CWE-120
Chain Complexity	2-step

Description: The framebuffer initialization code uses sprintf() to construct filesystem paths by concatenating user-controlled input (fb_) into fixed-size buffers. While malloc() allocates strlen(fb_) + 10/50 bytes, sprintf() does not perform bounds checking, allowing heap-based buffer overflow when fb_ contains long strings or format specifiers.

Evidence

Exploitation scenario: An attacker controlling the fb_ parameter (via command-line argument --framebuffer/-f) can supply a string that, when combined with format string literals, exceeds the allocated buffer size.

Scanner confirmation: multi_agent_ai rule V-001 flagged this pattern.

Production code: This file is in the production codebase, not test-only code.

Changes

• gpu/imgfb/imgfb.c

Note: The following lines in the same file use a similar pattern and may also need review: gpu/imgfb/imgfb.c:147, gpu/imgfb/imgfb.c:150, gpu/imgfb/imgfb.c:153

Behavior Preservation

The change is scoped to 1 file on the vulnerable path; it only tightens handling of untrusted input and leaves valid inputs unaffected.

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Automated security fix by OrbisAI Security