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wickwirew / Runtime

A Swift Runtime library for viewing type info, and the dynamic getting and setting of properties.
MIT License
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TypeInfo of class types crashes on linux for swift >= 5.4 #92

Closed Supereg closed 2 years ago

Supereg commented 3 years ago

Hello,

wanted to report that the Runtime framework crashes (segfault) when used on linux platforms using a swift compiler >= 5.4. To my analysis, it comes from calling typeInfo(of:) for any class type.

I noticed this in the environment of our own project https://github.com/Apodini/Apodini/pull/294, but could also easily reproduce it with the provided test cases of the Runtime framework.

The following test cases fail:

I found that any call to typeInfo(of:) with a class type will result in a segfault (see backtrace below). Specifically, it will most certainly fail when evaluating the mangledName() method (inside the ClassMetadata.toTypeInfo() call): https://github.com/wickwirew/Runtime/blob/5b82a3e74bd9fd5dfcad8e6ab8cc3f907aa4e235/Sources/Runtime/Metadata/NominalMetadataType.swift#L43

If you uncomment that line it will fail on the next access to the pointer.pointee.typeDescriptor.pointee chain (e.g. in NominalMetadataType.numberOfFields).

For context, I created some extensive GitHub Ci (see Supereg/Runtime feature/github-ci branch) which runs the tests cases in all swift 5 version for all common linux distributions available on the Swift DockerHub: GitHub CI Run Overview. It shows that since swift 5.4 every swift release on all linux platforms are affected. I'll plan to create a pull request for that later as well.

Below is an exemplary backtrace of the segfault happening when running the shown command under xenial.

swift test --filter GetSetClassTests
[4/4] Build complete!
Test Suite 'Selected tests' started at 2021-06-30 15:04:32.986
Test Suite 'GetSetClassTests' started at 2021-06-30 15:04:32.987
Test Case 'GetSetClassTests.testGet' started at 2021-06-30 15:04:32.987
Exited with signal code 11
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007f1de0332263 in swift::metadataimpl::ValueWitnesses<swift::metadataimpl::NativeBox<unsigned int, 4ul, 4ul, 4ul> >::initializeWithCopy(swift::OpaqueValue*, swift::OpaqueValue*, swift::TargetMetadata<swift::InProcess> const*) ()
   from /usr/lib/swift/linux/libswiftCore.so
#1  0x000055a47e1b7dec in $s7Runtime15RelativePointerV8advancedSpyq_GyF (self=<error reading variable: Cannot access memory at address 0x28>) at /usr/src/Runtime/Sources/Runtime/Pointers/RelativePointer.swift:31
#2  0x000055a47e1ac340 in $s7Runtime19NominalMetadataTypePAAE11mangledNameSSyF (self=...) at /usr/src/Runtime/Sources/Runtime/Metadata/NominalMetadataType.swift:43
#3  0x000055a47e1a79ef in $s7Runtime13ClassMetadataV10toTypeInfoAA0eF0VyF (self=...) at /usr/src/Runtime/Sources/Runtime/Metadata/ClassMetadata.swift:88
#4  0x000055a47e1a80ab in $s7Runtime13ClassMetadataVAA19TypeInfoConvertibleA2aDP02todE0AA0dE0VyFTW ()
#5  0x000055a47e1b60c6 in $s7Runtime8typeInfo2ofAA04TypeC0VypXp_tKF (type=...) at /usr/src/Runtime/Sources/Runtime/Models/TypeInfo.swift:81
#6  0x000055a47e1c1a09 in $s12RuntimeTests011GetSetClassB0C04testC0yyKF (self=...) at /usr/src/Runtime/Tests/RuntimeTests/GetSetClassTests.swift:60
#7  0x000055a47e1e9625 in $s12RuntimeTests011GetSetClassB0C05__allB0SaySS_yyKcACctGvpZfiyyKcACcfu_yyKcfu0_ () at /usr/src/Runtime/Tests/RuntimeTests/XCTestManifests.swift:13
#8  0x000055a47e1f02af in $s12RuntimeTests011GetSetClassB0C05__allB0SaySS_yyKcACctGvpZfiyyKcACcfu_yyKcfu0_TA ()
#9  0x000055a47e1bb16f in $ss5Error_pIegzo_ytsAA_pIegrzo_TR ()
#10 0x000055a47e1ca944 in $ss5Error_pIegzo_ytsAA_pIegrzo_TRTA ()
#11 0x00007f1de0618b5c in $syts5Error_pIegrzo_sAA_pIegzo_TRTA () from /usr/lib/swift/linux/libXCTest.so
#12 0x00007f1de06189b8 in $s6XCTest4test33_3BE257A46ADB477C7BF2D39968B39F9DLLyyAA0A4CaseCKcyyKcxcAERbzlFyAEKcfU_TA () from /usr/lib/swift/linux/libXCTest.so
#13 0x00007f1de061894f in $s6XCTest0A4CaseCs5Error_pIeggzo_ACytsAD_pIegnrzo_TRTA () from /usr/lib/swift/linux/libXCTest.so
#14 0x00007f1de0618c16 in $s6XCTest0A4CaseCs5Error_pIeggzo_ACytsAD_pIegnrzo_TRTA.19 () from /usr/lib/swift/linux/libXCTest.so
#15 0x00007f1de060a628 in $s6XCTest0A4CaseCyts5Error_pIegnrzo_ACsAD_pIeggzo_TRTA () from /usr/lib/swift/linux/libXCTest.so
#16 0x00007f1de06172f8 in $s6XCTest0A4CaseC10invokeTestyyF () from /usr/lib/swift/linux/libXCTest.so
#17 0x00007f1de06170e3 in $s6XCTest0A4CaseC7performyyAA0A3RunCF () from /usr/lib/swift/linux/libXCTest.so
#18 0x00007f1de061a980 in $s6XCTestAAC3runyyF () from /usr/lib/swift/linux/libXCTest.so
#19 0x00007f1de0618eaf in $s6XCTest0A5SuiteC7performyyAA0A3RunCF () from /usr/lib/swift/linux/libXCTest.so
#20 0x00007f1de061a980 in $s6XCTestAAC3runyyF () from /usr/lib/swift/linux/libXCTest.so
#21 0x00007f1de0618eaf in $s6XCTest0A5SuiteC7performyyAA0A3RunCF () from /usr/lib/swift/linux/libXCTest.so
#22 0x00007f1de061a980 in $s6XCTestAAC3runyyF () from /usr/lib/swift/linux/libXCTest.so
#23 0x00007f1de0615d24 in $s6XCTest7XCTMain_9arguments9observerss5NeverOSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGtF () from /usr/lib/swift/linux/libXCTest.so
#24 0x00007f1de06156eb in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF () from /usr/lib/swift/linux/libXCTest.so
#25 0x000055a47e1bace1 in main () at /usr/src/Runtime/Tests/LinuxMain.swift:8

Happy to help if I can provide any further assistance.

Supereg commented 3 years ago

Reading through the ABI docs, might this be related to the following change: https://github.com/apple/swift/commit/38fc849a1fc8ea703de2fd1f280b43c682b70257#diff-22fb9f1513d9c05f34d493826b4553bba65a4336a41ae4413678feec549db3a5?

It reads like that on platforms without Objective-C interoperability the objCRuntimeReserve and rodataPointer fields are not present anymore.

Judging by the git tags, this change was introduced with swift 5.4

Supereg commented 3 years ago

Alright, I think I got it fixed. Successfully passes on all swift versions on all linux platforms (see my Action Run, note the swiftlang/swift:nightly-xenial which is failing. The tag is actually 9 months old and contains a swift 5.3 dev version which seemingly has the changed class metadata layout).