Guard val_mem_copy against buffer overflow

[jk-arm]

Summary

• add a destination-size parameter to val_mem_copy and clamp copies to it
• update the only caller to pass the buffer span

Testing

• Not run (not requested)

[Copilot]

Pull request overview

This PR adds buffer overflow protection to the val_mem_copy function by introducing a destination size parameter and clamping copy operations to prevent writing beyond buffer boundaries. It also adds format string checking attributes for val_printf on GCC and Clang compilers.

• Added dest_size parameter to val_mem_copy with bounds checking
• Updated the single caller in val_common_log.c to pass the destination buffer size
• Added compiler-specific format string checking attributes to val_printf

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/val_common_framework.c	Implements bounds checking in val_mem_copy by adding dest_size parameter and clamping logic
inc/val_common_framework.h	Updates function signature to include new dest_size parameter
src/val_common_log.c	Updates caller to pass sizeof(formatted_msg) as destination size
inc/val_common_log.h	Adds format attribute macro for compile-time printf format checking

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[Copilot]

The clamping logic should account for null termination. When len equals dest_size, the code will write up to the last byte of the destination buffer, leaving no room for a null terminator if one is expected. Consider clamping to dest_size - 1 if the destination is intended to be a null-terminated string, or document that this function does not null-terminate.

[Copilot]

After the call to val_mem_copy, lines 636-638 write to indices len - 1, len, and len + 1 without checking if these indices are within the bounds of formatted_msg. If len is close to sizeof(formatted_msg), this could write beyond the buffer. The bounds check should be performed before these operations.