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Try loading with safe path using LOAD_LIBRARY_SEARCH_SYSTEM32 first

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* autoload.cc (dll_load): Move safe loading from std_dll_init here.
	Add code to handle systems supporting LOAD_LIBRARY_SEARCH flags.
	Add comments to explain what the code is doing.  Fix up comment
	preceeding this function.
	(std_dll_init): Move safe loading code to dll_load.
	* wincap.h (wincaps::has_load_lib_search_flags): New element.
        * wincap.cc: Implement above element throughout.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2016-01-12 15:23:14 +01:00
parent 27086d628e
commit 15d6f564cd
3 changed files with 43 additions and 18 deletions
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52
winsup/cygwin/autoload.cc
View File

@ -333,20 +333,44 @@ union retchain
};
/* This function is a workaround for the problem reported here:
/* This function handles the problem described here:
http://www.microsoft.com/technet/security/advisory/2269637.mspx
https://msdn.microsoft.com/library/ff919712
It also contains a workaround for the problem reported here:
http://cygwin.com/ml/cygwin/2011-02/msg00552.html
and discussed here:
http://cygwin.com/ml/cygwin-developers/2011-02/threads.html#00007
To wit: winmm.dll calls FreeLibrary in its DllMain and that can result
in LoadLibraryExW returning an ERROR_INVALID_ADDRESS. */
in LoadLibraryExW returning an ERROR_INVALID_ADDRESS. */
static __inline bool
dll_load (HANDLE& handle, WCHAR *name)
dll_load (HANDLE& handle, PWCHAR name)
{
HANDLE h = LoadLibraryW (name);
if (!h && handle && wincap.use_dont_resolve_hack ()
&& GetLastError () == ERROR_INVALID_ADDRESS)
h = LoadLibraryExW (name, NULL, DONT_RESOLVE_DLL_REFERENCES);
HANDLE h;
/* On systems supporting LOAD_LIBRARY_SEARCH flags, try to load
explicitely from the system dir first. */
if (wincap.has_load_lib_search_flags ())
h = LoadLibraryExW (name, NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
if (!h)
{
WCHAR dll_path[MAX_PATH];
/* If that failed, try loading with full path, which sometimes
fails for no good reason. */
wcpcpy (wcpcpy (dll_path, windows_system_directory), name);
h = LoadLibraryW (dll_path);
/* If that failed according to the second problem outlined in the
comment preceeding this function. */
if (!h && handle && wincap.use_dont_resolve_hack ()
&& GetLastError () == ERROR_INVALID_ADDRESS)
h = LoadLibraryExW (dll_path, NULL, DONT_RESOLVE_DLL_REFERENCES);
/* Last resort: Try loading just by name. */
if (!h)
h = LoadLibraryW (name);
}
if (!h)
return false;
handle = h;
@ -420,18 +444,15 @@ std_dll_init ()
{
fenv_t fpuenv;
fegetenv (&fpuenv);
WCHAR dll_path[MAX_PATH];
DWORD err = ERROR_SUCCESS;
int i;
/* http://www.microsoft.com/technet/security/advisory/2269637.mspx */
wcpcpy (wcpcpy (dll_path, windows_system_directory), dll->name);
/* MSDN seems to imply that LoadLibrary can fail mysteriously, so,
since there have been reports of this in the mailing list, retry
several times before giving up. */
for (i = 1; i <= RETRY_COUNT; i++)
{
/* If loading the library succeeds, just leave the loop. */
if (dll_load (dll->handle, dll_path))
if (dll_load (dll->handle, dll->name))
break;
/* Otherwise check error code returned by LoadLibrary. If the
error code is neither NOACCESS nor DLL_INIT_FAILED, break out
@ -444,15 +465,10 @@ std_dll_init ()
}
if ((uintptr_t) dll->handle <= 1)
{
/* If LoadLibrary with full path returns one of the weird errors
reported on the Cygwin mailing list, retry with only the DLL
name. Only do this when the above retry loop has been exhausted. */
if (i > RETRY_COUNT && dll_load (dll->handle, dll->name))
/* got it with the fallback */;
else if ((func->decoration & 1))
if ((func->decoration & 1))
dll->handle = INVALID_HANDLE_VALUE;
else
api_fatal ("unable to load %W, %E", dll_path);
api_fatal ("unable to load %W, %E", dll->name);
}
fesetenv (&fpuenv);
}

7
winsup/cygwin/wincap.cc
View File

@ -52,6 +52,7 @@ wincaps wincap_xpsp2 __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:false,
has_broken_prefetchvm:false,
has_new_pebteb_region:false,
has_load_lib_search_flags:false,
};
wincaps wincap_2003 __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -86,6 +87,7 @@ wincaps wincap_2003 __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:false,
has_broken_prefetchvm:false,
has_new_pebteb_region:false,
has_load_lib_search_flags:false,
};
wincaps wincap_vista __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -120,6 +122,7 @@ wincaps wincap_vista __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:false,
has_broken_prefetchvm:false,
has_new_pebteb_region:false,
has_load_lib_search_flags:true,
};
wincaps wincap_7 __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -154,6 +157,7 @@ wincaps wincap_7 __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:true,
has_broken_prefetchvm:false,
has_new_pebteb_region:false,
has_load_lib_search_flags:true,
};
wincaps wincap_8 __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -188,6 +192,7 @@ wincaps wincap_8 __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:true,
has_broken_prefetchvm:false,
has_new_pebteb_region:false,
has_load_lib_search_flags:true,
};
wincaps wincap_10 __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -222,6 +227,7 @@ wincaps wincap_10 __attribute__((section (".cygwin_dll_common"), shared)) = {
has_processor_groups:true,
has_broken_prefetchvm:true,
has_new_pebteb_region:false,
has_load_lib_search_flags:true,
};
wincaps wincap_10_1511 __attribute__((section (".cygwin_dll_common"), shared)) = {
@ -256,6 +262,7 @@ wincaps wincap_10_1511 __attribute__((section (".cygwin_dll_common"), shared)) =
has_processor_groups:true,
has_broken_prefetchvm:false,
has_new_pebteb_region:true,
has_load_lib_search_flags:true,
};
wincapc wincap __attribute__((section (".cygwin_dll_common"), shared));

2
winsup/cygwin/wincap.h
View File

@ -45,6 +45,7 @@ struct wincaps
unsigned has_processor_groups : 1;
unsigned has_broken_prefetchvm : 1;
unsigned has_new_pebteb_region : 1;
unsigned has_load_lib_search_flags : 1;
};
class wincapc
@ -104,6 +105,7 @@ public:
bool IMPLEMENT (has_processor_groups)
bool IMPLEMENT (has_broken_prefetchvm)
bool IMPLEMENT (has_new_pebteb_region)
bool IMPLEMENT (has_load_lib_search_flags)
#undef IMPLEMENT
};