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w32: use safe DLL search paths everywhere

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Windows applications that use LoadLibrary are vulnerable to DLL
preloading attacks if a malicious DLL with the same name as a system DLL
is placed in the current directory. mpv had some code to avoid this in
ao_wasapi.c. This commit just moves it to main.c, since there's no
reason it can't be used process-wide.

This change can affect how plugins are loaded in AviSynth, but it
shouldn't be a problem since MPC-HC also does this and it's a very
popular AviSynth client.
This commit is contained in:
James Ross-Gowan 2014-01-07 23:26:26 +11:00 committed by wm4
parent 4c83a93617
commit d26ee98fa6
2 changed files with 21 additions and 17 deletions
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17
audio/out/ao_wasapi.c
View File

@ -36,10 +36,6 @@
#include "misc/ring.h"
#include "ao.h"
#ifndef BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE
#define BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE 0x00000001
#endif
#ifndef PKEY_Device_FriendlyName
DEFINE_PROPERTYKEY(PKEY_Device_FriendlyName,
0xa45c254e, 0xdf1c, 0x4efd, 0x80, 0x20,
@ -136,17 +132,6 @@ static int fill_VistaBlob(wasapi_state *state)
{
if (!state)
return 1;
HMODULE hkernel32 = GetModuleHandleW(L"kernel32.dll");
if (!hkernel32)
return 1;
WINBOOL (WINAPI *pSetDllDirectory)(LPCWSTR lpPathName) =
(WINBOOL (WINAPI *)(LPCWSTR))GetProcAddress(hkernel32, "SetDllDirectoryW");
WINBOOL (WINAPI *pSetSearchPathMode)(DWORD Flags) =
(WINBOOL (WINAPI *)(DWORD))GetProcAddress(hkernel32, "SetSearchPathMode");
if (pSetSearchPathMode)
pSetDllDirectory(L""); /* Attempt to use safe search paths */
if (pSetSearchPathMode)
pSetSearchPathMode(BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE);
state->VistaBlob.hAvrt = LoadLibraryW(L"avrt.dll");
if (!state->VistaBlob.hAvrt)
goto exit_label;
@ -160,8 +145,6 @@ static int fill_VistaBlob(wasapi_state *state)
exit_label:
if (state->VistaBlob.hAvrt)
FreeLibrary(state->VistaBlob.hAvrt);
if (pSetSearchPathMode)
pSetDllDirectory(NULL);
return 1;
}

21
player/main.c
View File

@ -79,6 +79,14 @@
#if defined(__MINGW32__) || defined(__CYGWIN__)
#include <windows.h>
#ifndef BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE
#define BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE (0x0001)
#endif
#ifndef BASE_SEARCH_PATH_PERMANENT
#define BASE_SEARCH_PATH_PERMANENT (0x8000)
#endif
#endif
const char mp_help_text[] =
@ -265,6 +273,19 @@ static void osdep_preinit(int *p_argc, char ***p_argv)
// Enable heap corruption detection
HeapSetInformation(NULL, HeapEnableTerminationOnCorruption, NULL, 0);
HMODULE kernel32 = GetModuleHandleW(L"kernel32.dll");
WINBOOL (WINAPI *pSetDllDirectory)(LPCWSTR lpPathName) =
(WINBOOL (WINAPI *)(LPCWSTR))GetProcAddress(kernel32, "SetDllDirectoryW");
WINBOOL (WINAPI *pSetSearchPathMode)(DWORD Flags) =
(WINBOOL (WINAPI *)(DWORD))GetProcAddress(kernel32, "SetSearchPathMode");
// Always use safe search paths for DLLs and other files, ie. never use the
// current directory
if (pSetSearchPathMode)
pSetDllDirectory(L"");
if (pSetSearchPathMode)
pSetSearchPathMode(BASE_SEARCH_PATH_ENABLE_SAFE_SEARCHMODE);
#endif
terminal_init();