Ticket History #9109: memory leak on macos

>
> hello, I've found what I believe to be a memory leak on macos -- I've
> tried to narrow it down to a simple reproduction:
>
> ```c
> #include <stdbool.h>
> #include <stdio.h>
> #include <gssapi.h>
>
> int main(void) {
> for (int i = 0; i < 10; i += 1) {
> gss_cred_id_t cred = 0;
> OM_uint32 minor = 0;
> OM_uint32 ret = gss_acquire_cred(
> &minor, GSS_C_NO_NAME, 0, GSS_C_NO_OID_SET,
> GSS_C_INITIATE, &cred, NULL, NULL
> );
> if (ret == GSS_S_COMPLETE) {
> printf("no error\n");
> gss_release_cred(&minor, &cred);
> } else {
> printf("got error: %d\n", ret);
> }
> }
> }
> ```
>
> compiled using:
>
> ```bash
> gcc $(PKG_CONFIG_PATH=/opt/homebrew/Cellar/krb5/1.21.2/lib/pkgconfig/
> pkg-config krb5-gssapi --cflags --libs) t.c
> ```
>
> leaks shown using:
>
> ```bash
> leaks --atExit -- ./a.out
> ```
>
> note: I don't have gss set up in any way so the expected path of my
> program above is the error case:
>
> ```console
> $ ./a.out
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> got error: 458752
> ```
>
>
>
> this leak is the important one (the other is sort of expected, a
> global error message retrievable later and is not per-call):
>
> ```
>
> STACK OF 8 INSTANCES OF 'ROOT CYCLE: <OS_xpc_connection>':
> 19 dyld 0x1822eff28 start + 2236
> 18 a.out 0x102af7f00 main + 88
> 17 libgssapi_krb5.2.2.dylib 0x102bdac2c gss_acquire_cred + 36
> 16 libgssapi_krb5.2.2.dylib 0x102bdadc8
> gss_acquire_cred_from + 400
> 15 libgssapi_krb5.2.2.dylib 0x102bdb180 gss_add_cred_from + 624
> 14 libgssapi_krb5.2.2.dylib 0x102bf8d30
> spnego_gss_acquire_cred_from + 128
> 13 libgssapi_krb5.2.2.dylib 0x102bf8e8c get_available_mechs + 228
> 12 libgssapi_krb5.2.2.dylib 0x102bdadc8
> gss_acquire_cred_from + 400
> 11 libgssapi_krb5.2.2.dylib 0x102bdb180 gss_add_cred_from + 624
> 10 libgssapi_krb5.2.2.dylib 0x102be919c acquire_cred_from + 68
> 9 libgssapi_krb5.2.2.dylib 0x102be9894
> acquire_cred_context + 1664
> 8 libkrb5.3.3.dylib 0x102cf1a70
> krb5_cccol_have_content + 92
> 7 libkrb5.3.3.dylib 0x102cf1788
> krb5_cccol_cursor_next + 76
> 6 libkrb5.3.3.dylib 0x102cf44dc
> api_macos_ptcursor_next + 240
> 5 libkrb5.3.3.dylib 0x102cf49d4 get_primary_name + 124
> 4 libxpc.dylib 0x182388850
> xpc_connection_create_mach_service + 40
> 3 libxpc.dylib 0x182398f80
> _xpc_connection_create + 136
> 2 libdispatch.dylib 0x182497838
> _os_object_alloc_realized + 32
> 1 libobjc.A.dylib 0x1822abe00 class_createInstance + 64
> 0 libsystem_malloc.dylib 0x182488eb0
> _malloc_zone_calloc_instrumented_or_legacy + 92
> ====
> 47 (5.98K) << TOTAL >>
> ----
> 6 (784 bytes) ROOT CYCLE: <OS_xpc_connection 0x13e0065e0> [240]
> "com.apple.GSSCred" (from libkrb5.3.3.dylib) pid 599 [GSSCred]
> 3 (368 bytes) ROOT CYCLE: <OS_dispatch_mach 0x13e008400>
> [160] "com.apple.GSSCred" (from libkrb5.3.3.dylib)
> 1 (64 bytes) ROOT CYCLE: <calloc in _dispatch_unote_create
> CYCLE BACK TO <OS_xpc_connection 0x13e0065e0> [240]
> "com.apple.GSSCred" (from libkrb5.3.3.dylib) pid 599 [GSSCred]
> 1 (144 bytes) <calloc in _dispatch_unote_create 0x13e0084a0> [144]
> 2 (176 bytes) <calloc in _xpc_connection_cancel 0x13e0066d0> [32]
> 1 (144 bytes) <malloc in _vasprintf 0x13e0088b0> [144]
> ```
>
> seemingly from this code here:
> https://github.com/krb5/krb5/blob/ec71ac1cabbb3926f8ffaf71e1ad007e4e56e0e5/src/lib/krb5/ccache/cc_api_macos.c#L161-L224
>
> I'm on macos 13.5.2 arm64 and using krb5 1.21.2 from homebrew
>
> ```
> $ uname -a
>
> Darwin FJJ4YYCWYX.local 22.6.0 Darwin Kernel Version 22.6.0: Wed Jul
> 5 22:22:05 PDT 2023; root:xnu-8796.141.3~6/RELEASE_ARM64_T6000 arm64
> arm Darwin
> ```
>
> anthony

>
> Can you test just calling xpc_release() and not not xpc_connection_cancel()?
>
> Thanks.
>
>