GNU bug report logs - #35245
libltdl.so uses 32-bit search path in 64-bit mode in Solaris 11.4

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Vita Batrla <vitezslav.batrla <at> oracle.com>
To: bug-libtool <at> gnu.org
Subject: libltdl.so uses 32-bit search path in 64-bit mode in Solaris 11.4
Date: Fri, 12 Apr 2019 11:04:43 +0200

[Message part 1 (text/plain, inline)]

Hi all,

I noticed that 64-bit version of libtool's libltdl.so shipped in Solaris 11.4
is compiled with 32-bit search path. This mismatch leads causes a failure to
dynamically load a module using lt_dlopen() interface.

Here's an example of a 64-bit executable trying to dynamically load
"libcrypt.so":

$ truss -t open,mmapobj ./ltdldemo
openat(AT_FDCWD, "/var/ld/64/ld.config", O_RDONLY) Err#2 ENOENT
openat(AT_FDCWD, "/usr/lib/64/libltdl.so.7", O_RDONLY) = 3
openat(AT_FDCWD, "/lib/64/libc.so.1", O_RDONLY) = 3
calling lt_dlinit
calling lt_dlopen
openat(AT_FDCWD, "/usr/lib/libcrypt.so", O_RDONLY) = 3

^ found "libcrypt.so" in 32-bit path

mmapobj(3, MMOBJ_INTERPRET, 0x7FFFBF6ED210, 0x7FFFBFFFEA0C, 0x00000000) Err#48 ENOTSUP

^ failed to map it

libcrypt.so: file not found

I assume the failure is obvious. A 64-bit program doesn't like 32-bit
library (/usr/lib/libcrypt.so) and so mmapobj(2) syscall returns ENOTSUP
per its man page:

       ENOTSUP       The current user data model does not match the fd  to  be
                     interpreted.  For example, a 32-bit process that tried to
                     use mmapobj() to interpret a 64-bit object  would  return

The fix is to use 64-bit default search path in 64-bit mode (/lib/64
/usr/lib/64). There are two workarounds:

1. LTDL_LIBRARY_PATH=/lib/64:/usr/lib/64
2. re-compile 64-bit libtool:
     ./configure lt_cv_sys_dlsearch_path="/lib/64 /usr/lib/64"

Perhaps the best solution would be to auto-detect whether to use 32-bit or
64-bit library search paths [1][2][3] on Solaris OS in a configure script.

Please see a suggested fix in an attached patch.

Thanks,

Vita

[1] Search paths per ld(1) man page:
       LIBPATH        For  32-bit  libraries, the default search path is /lib,
                      followed by /usr/lib. For 64-bit libraries, the  default
                      search path is /lib/64, followed by /usr/lib/64.

[2] Search paths per ld.so.1(1) man page:
       The runtime linker uses a  prescribed  search  path  for  locating  the
       dynamic  dependencies  of  an  object. The default search paths are the
       runpath recorded in the object, followed by a series of  defaults.  For
       32-bit  objects, the defaults are /lib followed by /usr/lib. For 64-bit
       objects, the  defaults  are  /lib/64  followed  by  /usr/lib/64.

[3] Search paths per crle(1) man page:
           The  default  search paths for 32-bit ELF objects are /lib followed
           by /usr/lib. For 64-bit ELF objects, the default search  paths  are
           /lib/64 followed by /usr/lib/64.

[000-64-bit-sys_dlsearch_path.patch (text/plain, attachment)]

Message #8 received at 35245 <at> debbugs.gnu.org (full text, mbox):

From: Bob Friesenhahn <bfriesen <at> simple.dallas.tx.us>
To: Vita Batrla <vitezslav.batrla <at> oracle.com>
Cc: 35245 <at> debbugs.gnu.org, bug-libtool <at> gnu.org
Subject: Re: bug#35245: libltdl.so uses 32-bit search path in 64-bit mode in
 Solaris 11.4
Date: Wed, 24 Apr 2019 16:39:30 -0500 (CDT)

On Fri, 12 Apr 2019, Vita Batrla wrote:

> Hi all,
>
> I noticed that 64-bit version of libtool's libltdl.so shipped in Solaris 11.4
> is compiled with 32-bit search path. This mismatch leads causes a failure to
> dynamically load a module using lt_dlopen() interface.
>
> Here's an example of a 64-bit executable trying to dynamically load
> "libcrypt.so":

I agree with your problem statement and your patch, but would like to 
point out that loading a bare module name without a specified path is 
somewhat insecure and not a recommended use case.

I do not recall similar problems with failing to find 64-bit modules 
on my Solaris (and Solaris-derived) systems, but my software stores 
modules in a directory with a well defined path (a wise thing to do) 
and opens the ".la" module wrapper file via that path.  The libraries 
listed in the ".la" module are then loaded as expected.

In the mean time, Oracle could fix the libltdl.so shipped in Solaris 
11.4.

Bob
-- 
Bob Friesenhahn
bfriesen <at> simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt

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