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Summary:ASTERISK-14266: [patch] BASE64_DECODE() adds garbage end end of decoded string
Reporter:David Chappell (chappell)Labels:
Date Opened:2009-06-04 10:16:24Date Closed:2009-11-10 16:22:12.000-0600
Priority:MinorRegression?No
Status:Closed/CompleteComponents:Functions/func_base64
Versions:Frequency of
Occurrence
Related
Issues:
Environment:Attachments:( 0) base64_fix.patch
Description:This problem has two causes:

1) BASE64_DECODE() fails to null terminate its return value. This becomes evident if first a long string is decoded and then a short one.  The short one will have have the last part of the long string appended to it.

2) What is more, ast_base64decode() does not recognize the equals signs which pad the end of a string the length of which is not a multiple of three bytes. Rather than stopping, it decodes the padding as data, producing bogus output.  

****** ADDITIONAL INFORMATION ******

It appears that the patch in bug 0010979 was intended to fix part one of this problem.  However, it performed the null termination in ast_base64decode() rather than in BASE64_DECODE().  As pointed out in bug report 0011018, this resulted in truncation of RSA keys when the buffer provided to ast_base64decode() was of exactly the correct size.  So, the change was reverted, which caused the original bug to return.

I cannot find any reference to the second part of the problem in the bug tracker.
Comments:By: Mark Murawski (kobaz) 2009-09-09 15:21:33

In trunk, the base64 decoded string is properly null terminated now, but still doesn't stop after encountering an '='

main/utils.c: Line 270
-       while (*src && (cnt < max)) {
+       while (*src && (*src != '=') && (cnt < max)) {
By: Digium Subversion (svnbot) 2009-11-06 10:32:36.000-0600

Repository: asterisk
Revision: 228378

U   branches/1.4/funcs/func_base64.c
U   branches/1.4/main/utils.c

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r228378 | mnicholson | 2009-11-06 10:32:35 -0600 (Fri, 06 Nov 2009) | 8 lines

Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.

(closes issue ASTERISK-14266)
Reported by: chappell
Patches:
     base64_fix.patch uploaded by chappell (license 8)
Tested by: kobaz

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http://svn.digium.com/view/asterisk?view=rev&revision=228378
By: Digium Subversion (svnbot) 2009-11-06 13:52:48.000-0600

Repository: asterisk
Revision: 228620

_U  trunk/
U   trunk/funcs/func_base64.c
U   trunk/main/utils.c

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r228620 | mnicholson | 2009-11-06 13:52:47 -0600 (Fri, 06 Nov 2009) | 15 lines

Merged revisions 228378 via svnmerge from
https://origsvn.digium.com/svn/asterisk/branches/1.4

........
 r228378 | mnicholson | 2009-11-06 10:26:59 -0600 (Fri, 06 Nov 2009) | 8 lines
 
 Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.
 
 (closes issue ASTERISK-14266)
 Reported by: chappell
 Patches:
       base64_fix.patch uploaded by chappell (license 8)
 Tested by: kobaz
........

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=228620
By: Digium Subversion (svnbot) 2009-11-06 14:31:54.000-0600

Repository: asterisk
Revision: 228649

_U  branches/1.6.2/
U   branches/1.6.2/funcs/func_base64.c
U   branches/1.6.2/main/utils.c

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r228649 | mnicholson | 2009-11-06 14:31:53 -0600 (Fri, 06 Nov 2009) | 22 lines

Merged revisions 228620 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

................
 r228620 | mnicholson | 2009-11-06 13:47:11 -0600 (Fri, 06 Nov 2009) | 15 lines
 
 Merged revisions 228378 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/branches/1.4
 
 ........
   r228378 | mnicholson | 2009-11-06 10:26:59 -0600 (Fri, 06 Nov 2009) | 8 lines
   
   Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.
   
   (closes issue ASTERISK-14266)
   Reported by: chappell
   Patches:
         base64_fix.patch uploaded by chappell (license 8)
   Tested by: kobaz
 ........
................

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=228649
By: Digium Subversion (svnbot) 2009-11-06 14:42:46.000-0600

Repository: asterisk
Revision: 228650

_U  branches/1.6.1/
U   branches/1.6.1/funcs/func_base64.c
U   branches/1.6.1/main/utils.c

------------------------------------------------------------------------
r228650 | mnicholson | 2009-11-06 14:42:45 -0600 (Fri, 06 Nov 2009) | 22 lines

Merged revisions 228620 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

................
 r228620 | mnicholson | 2009-11-06 13:47:11 -0600 (Fri, 06 Nov 2009) | 15 lines
 
 Merged revisions 228378 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/branches/1.4
 
 ........
   r228378 | mnicholson | 2009-11-06 10:26:59 -0600 (Fri, 06 Nov 2009) | 8 lines
   
   Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.
   
   (closes issue ASTERISK-14266)
   Reported by: chappell
   Patches:
         base64_fix.patch uploaded by chappell (license 8)
   Tested by: kobaz
 ........
................

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=228650
By: Digium Subversion (svnbot) 2009-11-06 14:47:42.000-0600

Repository: asterisk
Revision: 228651

_U  branches/1.6.0/
U   branches/1.6.0/funcs/func_base64.c
U   branches/1.6.0/main/utils.c

------------------------------------------------------------------------
r228651 | mnicholson | 2009-11-06 14:47:42 -0600 (Fri, 06 Nov 2009) | 22 lines

Merged revisions 228620 via svnmerge from
https://origsvn.digium.com/svn/asterisk/trunk

................
 r228620 | mnicholson | 2009-11-06 13:47:11 -0600 (Fri, 06 Nov 2009) | 15 lines
 
 Merged revisions 228378 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/branches/1.4
 
 ........
   r228378 | mnicholson | 2009-11-06 10:26:59 -0600 (Fri, 06 Nov 2009) | 8 lines
   
   Properly handle '=' while decoding base64 messages and null terminate strings returned from BASE64_DECODE.
   
   (closes issue ASTERISK-14266)
   Reported by: chappell
   Patches:
         base64_fix.patch uploaded by chappell (license 8)
   Tested by: kobaz
 ........
................

------------------------------------------------------------------------

http://svn.digium.com/view/asterisk?view=rev&revision=228651