EXC_BAD_ACCESS if Address or Thread Sanitizer is enabled

Same here, started with iOS 18.4 I think. The crash happens before main.m is even entered, breakpoint in main.m is not reached. Before 18.4 it did. Did you find a solution?

Have you tried reproducing this with a small test project?

I just tried this here in my office and didn’t have a problem. Specifically:

1. Using Xcode 16.3 on macOS 15.4, I created a new app from the iOS > App template.

2. I ran it on the iPhone 16 simulator, simulating iOS 18.4. It launched successfully.

3. In the scheme editor I enabled Address Sanitizer.

4. I ran it again. It launched successfully.

5. In the scheme editor I disabled Address Sanitizer and enable Thread Sanitizer. It launched successfully.

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—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Thanks Quinn,

I'm sure a new and clean empty project runs, but this is a (big) existing project, objective-c, no storyboard but XIBs, that has run fine before 18.4, for years. As the crash happens before my code is even entered I don't even know where to start!

Does this Sanitizer message mean anything to you? What is the problem with MemoryMappingLayout?

libclang_rt.asan_iossim_dynamic.dylib__sanitizer::MemoryMappingLayout::Next: 0x10f2dae50 <+0>: cmpl $-0x1, 0x8(%rdi)`

With the sanitizers switched off in the Run Scheme the app runs fine in the Simulator, but I have a user that experiences an actual crash on device. That crash is different from what I experience: the app crashes on simulator before entering my code, after displaying the splash screen, while the user has an app that does startup, and can be used for a few seconds, but crashes on a certain input.

As is, I cannot even establish if these crashes are related.

In the App Analytics in AppstoreConnect I see no increase in the number of crashes for this app, 375k sessions/month, 98 crashes, so 0.25 promille.

(In the App Analytics in AppstoreConnect I see no increase in the number of crashes for this app, 375k sessions/month, 98 crashes, so 0.25 promille.)

Going to file a bug report, I think it is a bug in Xcode.

I'm sure a new and clean empty project runs

IME it’s best to actually verify such expectations, because:

• If your small test project fails, that suggests that you’re main project is fine and it’s likely that this is related to your environment.

• If it works, as you and I both expect, that gives you a known data point for some differential debugging.

Share and Enjoy
—
Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Bingo. Xcode Version 16.3 (16E140) New iOS App project, iOS 18.4, edit Scheme, switch on:

address sanitizer, 
  detect use of stack after return, 
undefined behavior sanitizer, 

main thread checker
thread performance checker

malloc scribble
zombie objects

api validation

And you get (iPhone 13 iOS 18.4 simulator):

`libclang_rt.asan_iossim_dynamic.dylib`__sanitizer::MemoryMappingLayout::Next:
    0x1100d9e50 <+0>:   cmpl   $-0x1, 0x8(%rdi)
    0x1100d9e54 <+4>:   jl     0x1100d9e7b               ; <+43>
    0x1100d9e56 <+6>:   pushq  %rbp
    0x1100d9e57 <+7>:   movq   %rsp, %rbp
    0x1100d9e5a <+10>:  pushq  %r15
    0x1100d9e5c <+12>:  pushq  %r14
...
 0x1100d9f54 <+260>: movl   0x4(%r13), %eax
    0x1100d9f58 <+264>: addq   %rax, %r13
->  0x1100d9f5b <+267>: movl   (%r13), %eax
    0x1100d9f5f <+271>: cmpl   $0xc, %eax
    0x1100d9f62 <+274>: jne    0x1100d9f50               ; <+256>

`

If you modify the App to run on iOS 18.0 (minimum deployment), add a simulator for iOS 18.0, you will find it runs fine on 18.0, with all those sanitizers on.

Will attach project to bug, eh feedback report FB17723761

This seems fixed with xcode Version 16.4 (16F6)