fix(lang): guard AccountLoader against buffer truncation

[swaroop-osec]

Summary

Adds buffer-size checks in AccountLoader::try_from and AccountLoader::exit. If the buffer is undersized:

• try_from returns AccountDidNotDeserialize (3003) up front instead of constructing a loader over a buffer that any subsequent load/load_mut/exit call would reject.
• exit returns AccountDidNotDeserialize (3003) instead of rewriting the discriminator over a truncated body and aborting the tx.

[vercel]

@swaroop-osec is attempting to deploy a commit to the OtterSec Team on Vercel.

A member of the Team first needs to authorize it.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	npm/​@​types/​node@​14.17.33 ⏵ 17.0.21			+2
	npm/​prettier@​2.8.0

View full report

[0x4ka5h]

lgtm now

[socket-security]

Warning

Review the following alerts detected in dependencies.

According to your organization's Security Policy, it is recommended to resolve "Warn" alerts. Learn more about Socket for GitHub.

Action	Severity	Alert  (click "▶" to expand/collapse)
Warn		Obfuscated code: npm prettier is 90.0% likely obfuscated Confidence: 0.90 Location: Package overview From: ts/packages/anchor-errors/package.json → npm/prettier@2.8.0 ℹ Read more on: This package | This alert | What is obfuscated code? Next steps: Take a moment to review the security alert above. Review the linked package source code to understand the potential risk. Ensure the package is not malicious before proceeding. If you're unsure how to proceed, reach out to your security team or ask the Socket team for help at support@socket.dev. Suggestion: Packages should not obfuscate their code. Consider not using packages with obfuscated code. Mark the package as acceptable risk. To ignore this alert only in this pull request, reply with the comment @SocketSecurity ignore npm/prettier@2.8.0. You can also ignore all packages with @SocketSecurity ignore-all. To ignore an alert for all future pull requests, use Socket's Dashboard to change the triage state of this alert.

View full report

[swaroop-osec]

@0x4ka5h Dropped the try_from check since it rejects valid-but-smaller legacy accounts before realloc can grow them (breaking zero-copy migrations), and load* already have size-check anyway. Kept the exit guard, which is the actual fix intended and added test covering the migration flow.

Please re-review