Memory leak in stream operators for `posix_time::time_duration`

[belyaev-ms]

Memory leak in stream operators for posix_time::time_duration

The << and >> operators for boost::posix_time::time_duration may cause memory leaks when an exception is thrown during memory allocation within these operators.

Steps to reproduce:

The following example simulates a memory allocation failure during the stream output operation for a time_duration variable. Custom new/delete operators are overloaded to force an exception on the 8th allocation call. The example should be built with AddressSanitizer (ASAN) to confirm the leak.

#include <vector>
#include <string>
#include <iostream>
#include <stdint.h>
#include <atomic>
#include <boost/date_time/posix_time/posix_time.hpp>

static std::atomic<int> fault_counter(-1);

void* operator new(std::size_t size)
{
    if (0 == size)
    {
        ++size;
    }

    if (fault_counter == -1 || fault_counter++ != 8)
    {
        void* ptr = malloc(size);
        if (ptr)
        {
            printf("[+] %p size=%lu\n", ptr, size);
            return ptr;
        }
    }
    printf("[!] FAULT size=%lu\n", size);
    throw std::bad_alloc{};
}

void operator delete(void* ptr) noexcept
{
    printf("[-] %p\n", ptr);
    std::free(ptr);
}

void operator delete(void* ptr, std::size_t ) noexcept
{
    printf("[-] %p\n", ptr);
    std::free(ptr);
}

int main(int , char** )
{
    try
    {
        puts("---------------------------------------");
        fault_counter = 0;
        boost::posix_time::time_duration td = boost::posix_time::seconds(60) + boost::posix_time::microsec(1000);
        std::ostringstream ss;
        ss << td;
        puts("---------------------------------------");
    }
    catch (...)
    {

    }
    return 0;
}

Live demonstration:
https://godbolt.org/z/zWo4Mdeac

Result (ASAN report):

=================================================================
==1==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 424 byte(s) in 1 object(s) allocated from:
    #0 0x7db40edd5c2b in malloc (/opt/compiler-explorer/gcc-15.2.0/lib64/libasan.so.8+0x121c2b)
    #1 0x0000004056ed in operator new(unsigned long) /app/example.cpp:19
    #2 0x00000040c062 in std::basic_ostream<char, std::char_traits<char> >& boost::posix_time::operator<< <char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, boost::posix_time::time_duration const&) /app/boost/include/boost/date_time/posix_time/posix_time_io.hpp:190
    #3 0x000000405ab9 in main /app/example.cpp:50
    #4 0x7db40e029d8f  (/lib/x86_64-linux-gnu/libc.so.6+0x29d8f)

... (additional indirect leaks reported) ...

SUMMARY: AddressSanitizer: 831 byte(s) leaked in 4 allocation(s).

Proposed fix:

The issue is in include/boost/date_time/posix_time/posix_time_io.hpp. The dynamically allocated facet objects are not deleted if an exception occurs during locale creation. The fix is to wrap the allocations in try-catch blocks and ensure proper cleanup.

diff --git a/include/boost/date_time/posix_time/posix_time_io.hpp b/include/boost/date_time/posix_time/posix_time_io.hpp
index 6a72e32..7da07c3 100644
--- a/include/boost/date_time/posix_time/posix_time_io.hpp
+++ b/include/boost/date_time/posix_time/posix_time_io.hpp
@@ -187,10 +187,20 @@ namespace posix_time {
       //since we would always need to reconstruct for every time period
       //if the locale did not already exist.  Of course this will be overridden
       //if the user imbues as some later point.
-      custom_ptime_facet* f = new custom_ptime_facet();
-      std::locale l = std::locale(os.getloc(), f);
-      os.imbue(l);
-      f->put(oitr, os, os.fill(), td);
+      custom_ptime_facet* f = nullptr;
+      try {
+        custom_ptime_facet* f = new custom_ptime_facet();
+        f_ = f;
+        std::locale l = std::locale(os.getloc(), f);
+        f_ = nullptr;
+        os.imbue(l);
+        f->put(oitr, os, os.fill(), td);
+      } catch(...) {
+        if(f_) {
+          delete f_;
+        }
+        throw;
+      }
     }
     return os;
   }
@@ -211,10 +221,20 @@ namespace posix_time {
           std::use_facet<time_input_facet_local>(is.getloc()).get(sit, str_end, is, td);
         }
         else {
-          time_input_facet_local* f = new time_input_facet_local();
-          std::locale l = std::locale(is.getloc(), f);
-          is.imbue(l);
-          f->get(sit, str_end, is, td);
+          time_input_facet_local* f_ = nullptr;
+          try {
+            time_input_facet_local* f = new time_input_facet_local();
+            f_ = f;
+            std::locale l = std::locale(is.getloc(), f);
+            f_ = nullptr;
+            is.imbue(l);
+            f->get(sit, str_end, is, td);
+          } catch(...) {
+            if(f_) {
+              delete f_;
+            }
+            throw;
+          }
         }
       }
       catch(...) {

This change ensures that if an exception is thrown during the creation of the locale, the dynamically allocated facet is properly deleted before rethrowing the exception.

posix_time_io.patch