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[Swift] Addresses a bug where verifier skips capacity when verifying ID on buffers #8413

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Merged
mustiikhalil merged 1 commit into from
Oct 4, 2024
Merged

[Swift] Addresses a bug where verifier skips capacity when verifying ID on buffers #8413

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2 changes: 2 additions & 0 deletions swift/Sources/FlatBuffers/FlatbuffersErrors.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@ import Foundation
/// Collection of thrown from the Flatbuffer verifier
public enum FlatbuffersErrors: Error, Equatable {

/// Thrown when trying to verify a buffer that doesnt have the length of an ID
case bufferDoesntContainID
/// Thrown when verifying a file id that doesnt match buffer id
case bufferIdDidntMatchPassedId
/// Prefixed size doesnt match the current (readable) buffer size
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4 changes: 4 additions & 0 deletions swift/Sources/FlatBuffers/Verifier.swift
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Expand Up @@ -201,8 +201,12 @@ public struct Verifier {
_depth -= 1
}

@inline(__always)
mutating func verify(id: String) throws {
let size = MemoryLayout<Int32>.size
guard _capacity >= (size * 2) else {
throw FlatbuffersErrors.bufferDoesntContainID
}
let str = _buffer.readString(at: size, count: size)
if id == str {
return
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11 changes: 11 additions & 0 deletions tests/swift/tests/Tests/FlatBuffers.Test.SwiftTests/FlatbuffersVerifierTests.swift
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Expand Up @@ -63,6 +63,17 @@ final class FlatbuffersVerifierTests: XCTestCase {
XCTAssertThrowsError(try Verifier(buffer: &buffer))
}

func testFailingID() {
let dutData : [UInt8] = [1,2,3,4,5,6,7]
var buff = ByteBuffer(bytes: dutData)
do {
let _: Monster = try getCheckedRoot(byteBuffer: &buff, fileId: "ABCD")
XCTFail("This should always fail")
} catch {
XCTAssertEqual(error as? FlatbuffersErrors, .bufferDoesntContainID)
}
}

func testVerifierCheckAlignment() {
var verifier = try! Verifier(buffer: &buffer)
do {
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