Fix potential buffer overflo when using XADRegex

[PaulTaykalo]

No description provided.

[Copilot]

Pull request overview

This PR addresses a potential out-of-bounds read / buffer overflow risk when using XADRegex to match against NSData buffers by ensuring the regex engine always receives a NUL-terminated byte buffer and by sanitizing invalid input ranges.

Changes:

• Add nullterminateddata storage and pass it to regexec to guarantee NUL-terminated input.
• Clamp NSRange inputs to valid bounds and handle nil NSData inputs safely.
• Add XCTest coverage for invalid/overflowing ranges and mutable-data snapshot behavior.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
XADRegex.m	Creates and uses a NUL-terminated buffer for regexec, clamps ranges, and manages added buffer lifetime.
XADRegex.h	Adds an ivar to retain the NUL-terminated buffer alongside the original data snapshot.
XADMasterTests/XADRegexTests.m	Adds unit tests covering invalid ranges and ensuring stable matching when input data is mutated after matching begins.
XADMaster.xcodeproj/project.pbxproj	Registers the new regex test file in the test target build phases/groups.
.gitignore	Ignores a local DerivedData build output path.

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[Copilot]

beginMatchingData:range: currently copies the entire input twice for mutable inputs (first via [data copy] into currdata, then again via [NSMutableData dataWithData:currdata] to create the null-terminated buffer). For large payloads this can significantly increase peak memory usage and may lead to avoidable memory pressure/OOM. Consider allocating a single buffer of datalength + 1 bytes, copying the source bytes once, and then (a) using that same backing store for currdata (length datalength, no free-on-done) and (b) keeping the owning NSMutableData as nullterminateddata for regexec.

Suggested change

	currdata=[data copy];
	[nullterminateddata release];
	NSMutableData *terminated=[NSMutableData dataWithData:currdata];
	[terminated appendBytes:"\0" length:1];
	nullterminateddata=[terminated retain];
	[nullterminateddata release];
	NSMutableData *terminated=[[NSMutableData alloc] initWithLength:datalength+1];
	void *terminatedbytes=[terminated mutableBytes];
	if(datalength>0) memcpy(terminatedbytes,[data bytes],datalength);
	((char *)terminatedbytes)[datalength]='\0';
	currdata=[[NSData alloc] initWithBytesNoCopy:terminatedbytes length:datalength freeWhenDone:NO];
	nullterminateddata=terminated;