[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: [libvirt] Stored secrets seem to get corrupted



On Tue, Jul 03, 2012 at 05:11:48PM +0200, Wido den Hollander wrote:
> Yes, there is memory corruption somewhere. I never used valgrind
> before, but the output seems to show.
> 
> I ran libvirtd inside a screen, I've attached the screenlog with all
> the output.
> 
> At the end you'll see there is a misread. I was storing the base64
> encoded value of "wido".

Thanks so there are two errors shown by valgrind

==6825== Invalid read of size 1
==6825==    at 0x5769DBA: vfprintf (vfprintf.c:1624)
==6825==    by 0x58289D0: __vasprintf_chk (vasprintf_chk.c:68)
==6825==    by 0x509C727: virVasprintf (stdio2.h:199)
==6825==    by 0x508CFEA: virLogVMessage (logging.c:749)
==6825==    by 0x508D349: virLogMessage (logging.c:696)
==6825==    by 0x127AB0BC: secretSaveValue (secret_driver.c:297)
==6825==    by 0x127AB30A: secretSetValue (secret_driver.c:861)
==6825==    by 0x5130CF4: virSecretSetValue (libvirt.c:14457)
==6825==    by 0x41CC8F: remoteDispatchSecretSetValueHelper (remote_dispatch.h:10962)
==6825==    by 0x5174F84: virNetServerProgramDispatch (virnetserverprogram.c:416)
==6825==    by 0x5171260: virNetServerHandleJob (virnetserver.c:161)
==6825==    by 0x50990AD: virThreadPoolWorker (threadpool.c:143)
==6825==  Address 0x19cb3c64 is 0 bytes after a block of size 4 alloc'd
==6825==    at 0x4C29DB4: calloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6825==    by 0x508E32F: virAllocN (memory.c:128)
==6825==    by 0x127AB21B: secretSetValue (secret_driver.c:838)
==6825==    by 0x5130CF4: virSecretSetValue (libvirt.c:14457)
==6825==    by 0x41CC8F: remoteDispatchSecretSetValueHelper (remote_dispatch.h:10962)
==6825==    by 0x5174F84: virNetServerProgramDispatch (virnetserverprogram.c:416)
==6825==    by 0x5171260: virNetServerHandleJob (virnetserver.c:161)
==6825==    by 0x50990AD: virThreadPoolWorker (threadpool.c:143)
==6825==    by 0x5098755: virThreadHelper (threads-pthread.c:161)
==6825==    by 0x550AE99: start_thread (pthread_create.c:308)
==6825==    by 0x58124BC: clone (clone.S:112)

This one is harmless - this is because the VIR_DEBUG line you added
uses '%s' to print secret_value, but this is not a NULL terminated
string. So we can ignore this.


==6825== 
==6825== Invalid read of size 4
==6825==    at 0xA57E4B9: base64_encode (in /usr/lib/x86_64-linux-gnu/libroken.so.18.1.0)
==6825==    by 0x10DDBC98: base64_encode_alloc (base64.c:140)
==6825==    by 0x127AB0EF: secretSaveValue (secret_driver.c:302)
==6825==    by 0x127AB30A: secretSetValue (secret_driver.c:861)
==6825==    by 0x5130CF4: virSecretSetValue (libvirt.c:14457)
==6825==    by 0x41CC8F: remoteDispatchSecretSetValueHelper (remote_dispatch.h:10962)
==6825==    by 0x5174F84: virNetServerProgramDispatch (virnetserverprogram.c:416)
==6825==    by 0x5171260: virNetServerHandleJob (virnetserver.c:161)
==6825==    by 0x50990AD: virThreadPoolWorker (threadpool.c:143)
==6825==    by 0x5098755: virThreadHelper (threads-pthread.c:161)
==6825==    by 0x550AE99: start_thread (pthread_create.c:308)
==6825==    by 0x58124BC: clone (clone.S:112)
==6825==  Address 0xb7786c8 is 8 bytes inside a block of size 9 alloc'd
==6825==    at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==6825==    by 0xA57E3D7: base64_encode (in /usr/lib/x86_64-linux-gnu/libroken.so.18.1.0)
==6825==    by 0x10DDBC98: base64_encode_alloc (base64.c:140)
==6825==    by 0x127AB0EF: secretSaveValue (secret_driver.c:302)
==6825==    by 0x127AB30A: secretSetValue (secret_driver.c:861)
==6825==    by 0x5130CF4: virSecretSetValue (libvirt.c:14457)
==6825==    by 0x41CC8F: remoteDispatchSecretSetValueHelper (remote_dispatch.h:10962)
==6825==    by 0x5174F84: virNetServerProgramDispatch (virnetserverprogram.c:416)
==6825==    by 0x5171260: virNetServerHandleJob (virnetserver.c:161)
==6825==    by 0x50990AD: virThreadPoolWorker (threadpool.c:143)

This one is very interesting. It shows that the 'base64_encode' function
is doing an out-of-bounds read. More tellingly though is that it is
reporting 'base64_encode' function is in a wierd library:

   /usr/lib/x86_64-linux-gnu/libroken.so.18.1.

If this were normal, we should expect to see that function present
in 'base64.c' since this function code is provided by gnulib itself.

So something else libvirt is linking to, directly or indirectly
is using  libroken.so which also has a 'base64_encode'symbol
defined. This is overriding gnulib's symbol of the same name.

I'm willing to bet the API contract of this libroken.so base64_encode.
differs from GNULIBS, with crashtastic results

Can you try and find how this libroken.so is getting linked to libvirt ?

Or indeed what this library does, or what package it is part of.

Regards,
Daniel
-- 
|: http://berrange.com      -o-    http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org              -o-             http://virt-manager.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org       -o-       http://live.gnome.org/gtk-vnc :|


[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]