[Passwdsecure-devel] Re: SEWL passwdsecure -- other note

[Andrew M. <ae...@bi...>]

Updated .c files attached

Richard,

Thanks for your input.  I have added an extra line to your supplied MD5File
function.  After the 16 unsigned chars have been placed as 32 string chars
(0-31), I added the string terminator char to array position 32 as follows:
    hexStringDigest[32] = '\0';

Regards

AndrewM

Andrew McGlashan AACS
Director

Mobile: 04 2574 1827

Affinity Vision Australia Pty Ltd
ABN 91 099 273 855

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----- Original Message -----
From: "Harris, Richard" <ha...@ta...>
To: "'Andrew McGlashan'" <ae...@bi...>; "Harris, Richard"
<ha...@ta...>
Cc: "Bill Lucas" <bil...@se...>; "Mario Piazzese"
<Mar...@se...>; <pas...@li...>
Sent: Friday, May 10, 2002 3:18 PM
Subject: RE: SEWL passwdsecure -- other note


> Hi Andrew,
>
> Looking at the truss output the problem seem symtematic of a buffer
overrun
> or a stray pointer being accessed.  I've had a look at authprocess.c and
> found a couple of strong contenders.
>
> You've changed the way MD5File works so it returns the MD5 data as a hex
> string, rather than the raw MD5 data.  I assume you've done this for the
> purposes of debugging so you can see the checksum more easily.  You've
made
> a few mistakes in doing this.
>
> Firstly, in MD5File (if the digest is calculated correctly) you return
> buffer2, unfortunately buffer2 is on the stack so as soon as you return
from
> MD5File the memory where you are pointing to will no longer exist.  Later
on
> you then call free on the returned value, this will cause all sorts of
> confusion!  Also digest is being created on the heap but you don't return
a
> pointer to it so it creates a memory leak.
>
> To do it your way MD5File should be:
>
> #ifdef USE_MD5
> char* MD5File(char* filename)
> {
> FILE* file;
> if ((file = fopen (filename, "rb")) == NULL)
> {
>
> #ifdef DEBUG
> fprintf(stderr, "Problem opening file: %s ...\n", filename);
> #endif
>
> return (char*)NULL;
> }
> else {
> MD5_CTX context;
> int len;
> unsigned char buffer[1024];
> unsigned char digest[16];
> unsigned int i;
> char* hexStringDigest;
>
> MD5Init (&context);
> while (len = fread (buffer, 1, 1024, file))
> MD5Update (&context, buffer, len);
> MD5Final (digest, &context);
>
> fclose (file);
>
> /* 33 chars, 32 for hexString, and 1 for NULL */
> hexStringDigest = (char*)malloc(sizeof(char)*33);
> checkMalloc((void*)hexStringDigest);
>
> for (i = 0; i < 16; i++)
> {
> sprintf(hexStringDigest + i*2, "%02x", digest[i] );
> }
>
> return hexStringDigest;
> }
> }
> #endif
>
> I havn't got a machine to compile this on to test but it looks all right.
>
> The other big problem is with md5thusfar.  At line 144 you define
md5thusfar
> as a char* and then (at line 220) you call strncpy to it before it is
> initialised.  It might be pointing at anything at this stage.
>
> You need to change line 220 from:
> strncpy(md5thusfar, file[0], 32);
> to:
> md5thusfar = (char*)malloc(sizeof(char)*33);
> checkMalloc((void*)md5thusfar);
> strncpy(md5thusfar, file[0], 32);
> md5thusfar[32] = '\0';
>
> Note the last line, if file[0] is 32 or more characters long then
md5thusfar
> won't finish with a null, so trouble will ensue.
>
> That's all of the problems I can see in authprocess.c at the moment.  If
you
> fix those problems you should be in with a much better shot of getting it
to
> work.
>
> Regards,
> Richard
>
> PS: As a formatting point when you have something like:
> <tab>func(first_arg,
> <tab>     second_arg);
> You shouldn't change it to
> <tab>func(first_arg,
> <tab><tab>second_arg);
> As the arguments won't line up if someone is using different sized tab
> stops.  You should always tab to specify indents and space to line up a
> command the spreads multiple lines.  The same applies for if/while
> conditions and for statements.
>
> PPS: I've made you an admin of the sourceforge project.
>
>
> -----Original Message-----
> From: Andrew McGlashan [mailto:ae...@bi...]
> Sent: Thursday, 9 May 2002 10:45 AM
> To: Harris, Richard
> Cc: Bill Lucas; Mario Piazzese
> Subject: Fw: SEWL passwdsecure -- other note
> Importance: High
>
>
> Richard,
>
> I have made this email high priority as SE Water has a number of uses that
> will need to use the passwdsecure tool.  Bill has even suggested that I be
> listed as a maintainer to try to progress this quicker; I would really
like
> some more help.
>
> Okay, I have looked at FILECMP again -- I broke it with my former MD5CHECK
> works.  I have since re-worked that but I still have some problems.  The
> FILEICMP looks okay after all, although I haven't actually tested it; I
> didn't look at it closely enough to understand it before.
>
> The problem I am having now with the re-worked FILECMP / MD5CHECK section
> having been done has to do with the getPsinfo function; it is dropping out
> without completing all checks.  I don't know why it dumps out, but here is
> the statement that is failing:
>
>     sizeRead = fread(buf+sizeReadTotal, 1, sizeof(psinfo_t)-sizeReadTotal,
> fileinfo);
>
> Other information (from the non-Linux code):
> > Checking file types / sizes...
> >
> > int      sizeRead         /* always 336 if successful */
> > int      sizeReadTotal    /* always 0 */
> >
> >
> > unsigned char buf[sizeof(psinfo_t)]
> >
>
> Now it fails after a number of iterations.  I did remove a single check
from
> one require group and it got through to an additional require group.  I
was
> going to include the output file with the debug information, but I don't
> have it with me right now.  Let me know if you need it and I will
endeavour
> to get it to you.
>
> I did adjust the following in the getPsinfo function:
>     from    FILE* fileinfo;
>     to    FILE *fileinfo;
> I assume that was simply a typo. The change didn't help or seem to effect
> anything.  I also made sure that every fopen had an fclose; I thought that
> maybe there were too many files open or something like that.  Maybe there
is
> still something in this as it was quite late when I packed it in last
night.
>
> The Makefile in the attached source has a DEBUG entry added to the CFLAGS
> line, so it always makes the debug version for now.  My 'do_conf' doesn't
> include the MD5 directory, however, it uses the found OpenSSL libraries
and
> thus the configure defines USE_MD5.
>
> AndrewM
>
> Andrew McGlashan AACS
> Director
>
> Mobile: 04 2574 1827
>
> Affinity Vision Australia Pty Ltd
> ABN 91 099 273 855
>
> This message contains privileged and confidential information intended
only
> for the use of the addressee named above. If you are not the intended
> recipient of this message you are hereby notified that you must not
> disseminate, copy or take any action in reliance on it.  If you have
> received this message in error please notify Affinity Vision Australia Pty
> Ltd at ae...@bi...  Any views expressed in this message are those of
the
> individual sender, except where the sender specifically states them to be
> the views of Affinity Vision Australia Pty Ltd
>
> ----- Original Message -----
> From: <And...@se...>
> To: <ae...@bi...>
> Sent: Thursday, May 09, 2002 1:12 AM
> Subject: SEWL passwdsecure -- other note
>
>
> >
> > The following statement fails consistently for unknown reasons.....,
> > but only after so many reads...
> >
> > sizeRead = fread(buf+sizeReadTotal, 1, sizeof(psinfo_t)-sizeReadTotal,
> > fileinfo);
> >
> >
> > Checking file types / sizes...
> >
> > int      sizeRead         /* always 336 if successful */
> > int      sizeReadTotal    /* always 0 */
> >
> >
> > unsigned char buf[sizeof(psinfo_t)]
> >
>
>
>
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