SafeFetch leads to hard crash on macOS 14.4

[Stefan Karlsson]

Hi Maxim,

On 2024-03-12 08:12, Maxim Kartashev wrote:
> Hello!
>
> This has been recently filed as 
> https://bugs.openjdk.org/browse/JDK-8327860 but I also wanted to check 
> with the community if any further info on the issue is available.
>
> It looks like in some cases SafeFetch is directed to fetch something 
> the OS really doesn't want it to and, instead of promoting the error 
> to a signal and letting the application (JVM) deal with it, 
> immediately terminates the application. All we've got is the OS crash 
> report, not even the JVM's fatal error log. This looks like an 
> application security precaution, which I am not at all familiar with.
>
> The relevant pieces of the crash log are below. Is anybody familiar 
> with "Namespace GUARD" termination reason and maybe other related 
> novelties of macOS 14.4? The error was not reported before upgrading 
> to 14.4

I don't have an answer for this, but a note below:

>
> Thanks in advance,
>
> Maxim.
>
> 0 libjvm.dylib 0x1062d6ec0 _SafeFetchN_fault + 0
> 1 libjvm.dylib 0x1062331a4 ObjectMonitor::TrySpin(JavaThread*) + 408
> 2 libjvm.dylib 0x106232b44 ObjectMonitor::enter(JavaThread*) + 228
> 3 libjvm.dylib 0x10637436c ObjectSynchronizer::enter(Handle, 
> BasicLock*, JavaThread*) + 392

FYI: I think that this specific call to SafeFetch was recently removed by:
https://github.com/openjdk/jdk/commit/29397d29baac3b29083b1b5d6b2cb06e456af0c3
https://bugs.openjdk.org/browse/JDK-8320317

Cheers,
StefanK


> ...
>
> Exception Type:        EXC_BAD_ACCESS (SIGKILL)
> Exception Codes:       KERN_PROTECTION_FAILURE at 0x00000001004f4000
> Exception Codes:       0x0000000000000002, 0x00000001004f4000
>
> Termination Reason:    Namespace GUARD, Code 5
>
> VM Region Info: 0x1004f4000 is in 0x1004f4000-0x1004f8000;  bytes 
> after start: 0  bytes before end: 16383
>       REGION TYPE                    START - END         [ VSIZE] 
> PRT/MAX SHRMOD  REGION DETAIL
>       mapped file                 1004e4000-1004f4000    [ 64K] 
> r--/r-- SM=COW  Object_id=fa8d88e7
> --->  VM_ALLOCATE                 1004f4000-1004f8000    [   16K] 
> ---/rwx SM=NUL
>       VM_ALLOCATE                 1004f8000-1004fc000    [ 16K] 
> r--/rwx SM=PRV