From:             phpbug dot exif at sub dot noloop dot net
Operating system: Linux
PHP version:      5.2CVS-2009-05-24 (snap)
PHP Bug Type:     EXIF related
Bug description:  exif_read_data() segfaults on certain corrupted .jpeg files

Description:
------------
There seems to be a problem in exif_read_data(), where some fields
representing offsets(?) are taken directly from the file without being
validated, resulting in a segmentation fault.

I originally found this issue by fooling around with the "zzuf" fuzzer,
and reported a very similar bug in the "jhead" exif utility at
http://bugs.debian.org/530401

Original image can be found at:
http://www.noloop.net/bugs/php/001-exif/hello.jpeg
Corrupted image can be found at:
http://www.noloop.net/bugs/php/001-exif/hello-s148.jpeg


Reproduce code:
---------------
<?php
 var_dump(exif_read_data($_SERVER['argv'][1], array("FILE", "COMPUTED",
"ANY_TAG") ));

Expected result:
----------------
Dump of exif data if possible, or FALSE (since the jpeg file is indeed
corrupt)

Actual result:
--------------
Segmentation fault.

Quick GDB dump:
(gdb) run
Starting program: /home/frode/temp/z/z3/php5.2-200905241830/sapi/cli/php
/home/frode/temp/z/s.php /home/frode/temp/z/a-s6.jpeg

Program received signal SIGSEGV, Segmentation fault.
0x0808bcd3 in exif_process_IFD_in_JPEG (ImageInfo=0xbfc893b8, 
    dir_start=0x92f76c0 <Address 0x92f76c0 out of bounds>,
offset_base=0x8ef76b8 "II*", IFDlength=15055, 
    displacement=30, section_index=3) at
/home/frode/temp/z/z3/php5.2-200905241830/ext/exif/exif.c:1088
1088                    return (((uchar *)value)[1] << 8) | ((uchar
*)value)[0];
(gdb) up
#1  0x0808e6ca in exif_read_file (ImageInfo=0xbfc893b8, FileName=<value
optimized out>, 
    read_thumbnail=<value optimized out>, read_all=0)
    at /home/frode/temp/z/z3/php5.2-200905241830/ext/exif/exif.c:3221
3221            exif_process_IFD_in_JPEG(ImageInfo, CharBuf+offset_of_ifd,
CharBuf, length/*-14*/, displacement, SECTION_IFD0 TSRMLS_CC);


Note the "dir_start" address being out of bounds, which causes the
"((uchar *)value)[1]" to segfault. (The function names are a bit confusing,
maybe it's because of method inlining?)

-- 
Edit bug report at http://bugs.php.net/?id=48378&edit=1
-- 
Try a CVS snapshot (PHP 5.2):        
http://bugs.php.net/fix.php?id=48378&r=trysnapshot52
Try a CVS snapshot (PHP 5.3):        
http://bugs.php.net/fix.php?id=48378&r=trysnapshot53
Try a CVS snapshot (PHP 6.0):        
http://bugs.php.net/fix.php?id=48378&r=trysnapshot60
Fixed in CVS:                        
http://bugs.php.net/fix.php?id=48378&r=fixedcvs
Fixed in CVS and need be documented: 
http://bugs.php.net/fix.php?id=48378&r=needdocs
Fixed in release:                    
http://bugs.php.net/fix.php?id=48378&r=alreadyfixed
Need backtrace:                      
http://bugs.php.net/fix.php?id=48378&r=needtrace
Need Reproduce Script:               
http://bugs.php.net/fix.php?id=48378&r=needscript
Try newer version:                   
http://bugs.php.net/fix.php?id=48378&r=oldversion
Not developer issue:                 
http://bugs.php.net/fix.php?id=48378&r=support
Expected behavior:                   
http://bugs.php.net/fix.php?id=48378&r=notwrong
Not enough info:                     
http://bugs.php.net/fix.php?id=48378&r=notenoughinfo
Submitted twice:                     
http://bugs.php.net/fix.php?id=48378&r=submittedtwice
register_globals:                    
http://bugs.php.net/fix.php?id=48378&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=48378&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=48378&r=dst
IIS Stability:                       
http://bugs.php.net/fix.php?id=48378&r=isapi
Install GNU Sed:                     
http://bugs.php.net/fix.php?id=48378&r=gnused
Floating point limitations:          
http://bugs.php.net/fix.php?id=48378&r=float
No Zend Extensions:                  
http://bugs.php.net/fix.php?id=48378&r=nozend
MySQL Configuration Error:           
http://bugs.php.net/fix.php?id=48378&r=mysqlcfg

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