programs using a static library and calling strdup() crash

programs using a static library and calling strdup() crash by attardi

Closed

as By Design Help for as By Design

Type:	Bug
ID:	333868
Opened:	3/21/2008 4:40:00 AM
Access Restriction:	Public

Workaround(s)

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User(s) can reproduce this bug

Any simple program that calls strdup() and links to a static library crashes with corrupted heap.

Notice that by replacing strdup() with _strdup() the program works, despite the fact that strdup() and _strdup() should be the same function: the documentation says that it is just a name change.

Details (expand)

English

Visual Studio 2008 (All Products and Editions)

Windows XP Professional

English

Compile the following program:

#include <cstdlib>
#include <cstring>
#include "zlib/zlib.h"

void bar() { inflateInit2_(); }

int main(int argc, char* argv[])
{
char const* dup = strdup(argv[0]);
free((void*)dup);
}

Where the static library contains just one file, inflate.c:

#include <stddef.h>

int inflateInit2_()
{
return 0;
}

with the corresponding header zlib.h

#ifndef ZLIB_H
#define ZLIB_H

#ifdef __cplusplus
extern "C" {
#endif

extern int inflateInit2_();

#ifdef __cplusplus
}
#endif

#endif /* ZLIB_H */

The thread 'Win32 Thread' (0x7dc) has exited with code 8388608 (0x800000).
HEAP[VS08bug.exe]: Invalid Address specified to RtlValidateHeap( 003F0000, 00483178 )
Windows has triggered a breakpoint in VS08bug.exe.

This may be due to a corruption of the heap, which indicates a bug in VS08bug.exe or any of the DLLs it has loaded.

Moreover, if the #include <stddef.h> is removed, the application fails to start with the message:

This application has failed to start because MSVCR90.dll was not found.

Termination with no errors.

File Name	Submitted By	Submitted On	File Size
VS08bug.zip (restricted)	attardi	3/21/2008	-

This is by design. Beppe, you're compiling the static library with /MD and the program with /MDd. So, when you run the application, both the Retail CRT and the Debug CRT (msvcr90.dll and msvcr90d.dll) are loaded at the same time.

The error you're seeing:

indicated there are some problem in the heap.

If you put a breakpoint in the call to strdup in main() you will see this callstack (we're calling the Retail CRT msvcr90.dll)

>    msvcr90.dll!_strdup(const char * string=0x009c1b90) Line 66    C
    VS08bug.exe!main(int argc=1, char * * argv=0x009c1b88) Line 17 + 0xe bytes    C++
    VS08bug.exe!__tmainCRTStartup() Line 582 + 0x19 bytes    C
    VS08bug.exe!mainCRTStartup() Line 399    C
    kernel32.dll!BaseThreadInitThunk(unsigned long RunProcessInit=0, long (void *)* StartAddress=0x00000000, void * Argument=0x7efde000) Line 817 + 0x5 bytes    C
    ntdll.dll!_RtlUserThreadStart(long (void *)* StartAddress=0x0028111d, void * Argument=0x7efde000) Line 2695    C

but the free() goes into the Debug CRT (msvcr90d.dll):

>    msvcr90d.dll!free(void * pUserData=0x00031220) Line 48    C++
    VS08bug.exe!main(int argc=1, char * * argv=0x009c1b88) Line 18 + 0xc bytes    C++
    VS08bug.exe!__tmainCRTStartup() Line 582 + 0x19 bytes    C
    VS08bug.exe!mainCRTStartup() Line 399    C
    kernel32.dll!BaseThreadInitThunk(unsigned long RunProcessInit=0, long (void *)* StartAddress=0x00000000, void * Argument=0x7efde000) Line 817 + 0x5 bytes    C
    ntdll.dll!_RtlUserThreadStart(long (void *)* StartAddress=0x0028111d, void * Argument=0x7efde000) Line 2695    C

The two CRTs have 2 different heaps. msvcr90d.dll!free will try to verify if the memory was allocated in the msvcr90d.dll heap, but that check will fail:

>    msvcr90d.dll!_CrtIsValidHeapPointer(const void * pUserData=0x00031220) Line 2103    C++
    msvcr90d.dll!_free_dbg_nolock(void * pUserData=0x00031220, int nBlockUse=1) Line 1317 + 0x9 bytes    C++
    msvcr90d.dll!_free_dbg(void * pUserData=0x00031220, int nBlockUse=1) Line 1258 + 0xd bytes    C++
    msvcr90d.dll!free(void * pUserData=0x00031220) Line 49 + 0xb bytes    C++
    VS08bug.exe!main(int argc=1, char * * argv=0x009c1b88) Line 18 + 0xc bytes    C++
    VS08bug.exe!__tmainCRTStartup() Line 582 + 0x19 bytes    C
    VS08bug.exe!mainCRTStartup() Line 399    C
    kernel32.dll!BaseThreadInitThunk(unsigned long RunProcessInit=0, long (void *)* StartAddress=0x00000000, void * Argument=0x7efde000) Line 817 + 0x5 bytes    C
    ntdll.dll!_RtlUserThreadStart(long (void *)* StartAddress=0x0028111d, void * Argument=0x7efde000) Line 2695    C

If you notice, the linker complained during compilation:

2>Linking...
2>LINK : warning LNK4098: defaultlib 'MSVCRT' conflicts with use of other libs; use /NODEFAULTLIB:library

If you compile the static library and the program with the same settings (both /MDd in Debug) then everything works ok.

HTH,
Ale Contenti
VC++ Libraries Dev Lead