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CFTimeZone: retain timezones stored in the name cache (use-after-free) #67

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CFTimeZone: retain timezones stored in the name cache (use-after-free) #67

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c72d895
CFTimeZone: retain timezones stored in the name cache
DTW-Thalion Jun 29, 2026
e62a6ef
CFTimeZone: add regression test for the name-cache use-after-free
DTW-Thalion Jun 29, 2026
ac6f02e
CFTimeZone: trim the regression-test comments
DTW-Thalion Jun 30, 2026
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3 changes: 2 additions & 1 deletion Source/CFTimeZone.c
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Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,8 @@ CFTimeZoneCreate (CFAllocatorRef alloc, CFStringRef name, CFDataRef data)
if (_kCFTimeZoneCache == NULL)
_kCFTimeZoneCache = CFDictionaryCreateMutable (
kCFAllocatorSystemDefault, 0,
&kCFCopyStringDictionaryKeyCallBacks, NULL);
&kCFCopyStringDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks);
GSMutexUnlock(&_kCFTimeZoneCacheLock);
}
/* Verify we haven't created a timezone with this name already. */
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34 changes: 34 additions & 0 deletions Tests/CFTimeZone/cache_retain.m
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Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
#include "CoreFoundation/CFBase.h"
#include "CoreFoundation/CFTimeZone.h"
#include "../CFTesting.h"

/* Regression test for the time-zone name cache use-after-free. */

int main (void)
{
CFTimeZoneRef tz1;
CFTimeZoneRef tz2;
CFStringRef name = CFSTR("America/New_York");

tz1 = CFTimeZoneCreateWithName (NULL, name, false);
if (tz1 == NULL)
{
/* zoneinfo for this name is not installed; nothing to exercise */
PASS_CF(1, "zoneinfo for America/New_York unavailable, skipping");
return 0;
}

/* Drop our own reference; the cache must still hold a live one. */
CFRelease (tz1);

/* Look the same name up again: the cache must own a live reference. */
tz2 = CFTimeZoneCreateWithName (NULL, name, false);
PASS_CF(tz2 != NULL,
"re-creating a released cached time zone returns a valid object");
PASS_CFEQ(CFTimeZoneGetName (tz2), name,
"the re-created time zone has the expected name");

CFRelease (tz2);

return 0;
}
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