[ruby-core:44381] [ruby-trunk - Bug #6303] dln_load and rb_w32_check_imported cause segfault in Ruby 1.9.3 for some extension

Issue #6303 has been updated by phasis68 (Heesob Park).


The segfault is due to the invalid pointer reference in getting PIMAGE_IMPORT_BY_NAME pointer like this:

PIMAGE_IMPORT_BY_NAME pii = (PIMAGE_IMPORT_BY_NAME)((char *)ext + (size_t)pint->u1.AddressOfData); 

Consider the following imports dump list of ibm_db.so

    DB2CLI.dll
              63317274 Import Address Table
              63317078 Import Name Table
                     0 time date stamp
                     0 Index of first forwarder reference

                      Ordinal  1300
                      Ordinal  1301
                   6C SQLDriverConnectW@32
                   52 SQLConnectW@28
                      Ordinal     9
                      Ordinal  1303
                      Ordinal    58
                   64 SQLDescribeColW@36
                      Ordinal     4
                   4A SQLColumnPrivilegesW@36
                   4E SQLColumnsW@36
                   FB SQLPrimaryKeysW@28
                   98 SQLForeignKeysW@52
                   FF SQLProcedureColumnsW@36
                  103 SQLProceduresW@28
                  133 SQLSpecialColumnsW@40
                  137 SQLStatisticsW@36
                  13B SQLTablePrivilegesW@28
                  13F SQLTablesW@36
                   7A SQLExecDirectW@12
                   F7 SQLPrepareW@12
...

As you can see, the name table entry has two types: ordinal type and name type.
But, the rb_w32_check_imported function overlooked ordinal case.

Refer to http://nienie.com/~masapico/api_ImageDirectoryEntryToData.html

Here is a patch:

diff --git a/dln.c b/dln.c.new
index e3dff9b..58042e1 100644
--- a/dln.c
+++ b/dln.c.new
@@ -1215,12 +1215,14 @@ rb_w32_check_imported(HMODULE ext, HMODULE mine)
 	PIMAGE_THUNK_DATA pint = (PIMAGE_THUNK_DATA)((char *)ext + desc->Characteristics);
 	PIMAGE_THUNK_DATA piat = (PIMAGE_THUNK_DATA)((char *)ext + desc->FirstThunk);
 	while (piat->u1.Function) {
-	    PIMAGE_IMPORT_BY_NAME pii = (PIMAGE_IMPORT_BY_NAME)((char *)ext + (size_t)pint->u1.AddressOfData);
-	    static const char prefix[] = "rb_";
-	    const char *name = (const char *)pii->Name;
-	    if (strncmp(name, prefix, sizeof(prefix) - 1) == 0) {
-		FARPROC addr = GetProcAddress(mine, name);
-		if (addr) return (FARPROC)piat->u1.Function == addr;
+	    if(!IMAGE_SNAP_BY_ORDINAL(pint->u1.Ordinal)) {
+	        PIMAGE_IMPORT_BY_NAME pii = (PIMAGE_IMPORT_BY_NAME)((char *)ext + (size_t)pint->u1.AddressOfData);
+	        static const char prefix[] = "rb_";
+	        const char *name = (const char *)pii->Name;
+	        if (strncmp(name, prefix, sizeof(prefix) - 1) == 0) {
+		    FARPROC addr = GetProcAddress(mine, name);
+		    if (addr) return (FARPROC)piat->u1.Function == addr;
+	        }
 	    }
 	    piat++;
 	    pint++;


----------------------------------------
Bug #6303:  dln_load and rb_w32_check_imported cause segfault in Ruby 1.9.3 for some extension
https://bugs.ruby-lang.org/issues/6303#change-25925

Author: luislavena (Luis Lavena)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 


 Hello,
 
 NOTE: Reporting this here since bugs.ruby-lang.org seems to be down.
 
 Recently a user reported to RubyInstaller project issues when loading
 a Ruby 1.9.2 compiled extension under Ruby 1.9.3:
 
 https://groups.google.com/d/msg/rubyinstaller/aSezE2LwfQs/TDZvPG3X5mUJ
 
 Which I was able to study a bit better:
 https://groups.google.com/d/msg/rubyinstaller/aSezE2LwfQs/UGKlButpNfMJ
 
 To add more, my last comment was:
 
 "Is worth to mention that this do not fail against 1.9.2 (either
 building or running) but dln_load mechanism on Ruby 1.9.2 differs from
 Ruby 1.9.3 and highly unlikely is going to change."
 
 I'm not convinced by my last comment and I do believe this is a bug.
 db2cli.dll links to MSVCR80 and even so, it loads properly under
 1.9.2.
 
 Looking closely to what rb_w32_check_imported does, it is supposed to
 verify that the extension being loaded it is indeed using the right
 ruby dll.
 
 But is failing to obtain Name from pii (PIMAGE_IMPORT_BY_NAME struct)
 
 I can't find any reference to dbghelp (which provides
 ImageDirectoryEntryToData) being included or linked in
 msvcrt-libruby191.dll
 
 For sure I'm missing something, specially why is failing to obtain
 this extension information when works for others.
 
 Thank you.
 -- 
 Luis Lavena
 AREA 17
 -
 Perfection in design is achieved not when there is nothing more to add,
 but rather when there is nothing more to take away.
 Antoine de Saint-Exup辿ry


-- 
http://bugs.ruby-lang.org/