Tickets :: [#8761] Divide by zero error in /ansel/lib/Exif.php

6.0.0-beta1

7/18/25

Summary	Divide by zero error in /ansel/lib/Exif.php
Queue	Ansel
Queue Version	1.1
Type	Bug
State	Resolved
Priority	1. Low
Owners	mrubinsk (at) horde (dot) org
Requester	jon (at) spriggs (dot) org (dot) uk
Created	12/08/2009 (5701 days ago)
Due
Updated	01/13/2010 (5665 days ago)
Assigned	12/09/2009 (5700 days ago)
Resolved	12/13/2009 (5696 days ago)
Github Issue Link
Github Pull Request
Milestone
Patch	Yes

01/13/2010 12:17:46 AM	CVS Commit	Comment #7	Reply to this comment
Changes have been made in Git for this ticket: Protect against division by zero from faulty exif data. ~~Bug: 8761~~ http://git.horde.org/diff.php/framework/Image/lib/Horde/Image/Exif.php?rt=horde-git&r1=6b4e0ea33bc6cfa1269e6dca4f56f89f421921c0&r2=e2c90271b152af30c18674bef5e93e742b90097e

12/13/2009 11:45:03 PM	Michael Rubinsky	Comment #6 State ⇒ Resolved	Reply to this comment
Seems like the php native exif functions return invalid data for some fields when the value is not defined in the image source. Fixed, though instead of returning zero like your patch did, we simply return from the function, since the value of x/0 is not 0, but undefined. Thanks for the catch!

12/13/2009 11:42:45 PM	CVS Commit	Comment #5	Reply to this comment
Changes have been made in Git for this ticket: Protect against division by zero from faulty exif data. ~~Bug: 8761~~ http://git.horde.org/diff.php/framework/Image/lib/Horde/Image/Exif.php?rt=horde-hatchery&r1=6b4e0ea33bc6cfa1269e6dca4f56f89f421921c0&r2=e2c90271b152af30c18674bef5e93e742b90097e

12/13/2009 11:38:31 PM	CVS Commit	Comment #4	Reply to this comment
Changes have been made in CVS for this ticket: Protect from divide-by-zero errors due to faulty exif data. ~~Bug: 8761~~ Submitted by: jon (at) spriggs (dot) org (dot) uk http://cvs.horde.org/diff.php/ansel/lib/Exif.php?rt=horde&r1=1.41.2.11&r2=1.41.2.12&ty=u

12/09/2009 10:44:00 AM	jon (at) spriggs (dot) org (dot) uk	Comment #3	Reply to this comment
Looks like there are lots of places in Exifer's original code that this should be checked...OTOH, the exif standard says that values for those fields shouldn't contain a zero denominator and are rational numbers. What is the source of the exif information that is broken? Can you upload a sample image file? I'm on my phone right now which has uploads disabled. The file is at http://jon.spriggs.org.uk/exif_error.jpg Also, please read docs/CODING_STANDARDS when submitting future patches, and thanks! Will do. Jon

12/09/2009 01:32:11 AM	Michael Rubinsky	Comment #2 State ⇒ Feedback	Reply to this comment
Looks like there are lots of places in Exifer's original code that this should be checked...OTOH, the exif standard says that values for those fields shouldn't contain a zero denominator and are rational numbers. What is the source of the exif information that is broken? Can you upload a sample image file? Also, please read docs/CODING_STANDARDS when submitting future patches, and thanks!

12/08/2009 11:19:47 PM	Chuck Hagenbuch	State ⇒ Assigned Assigned to Michael Rubinsky

12/08/2009 10:42:07 PM	jon (at) spriggs (dot) org (dot) uk	Comment #1 Priority ⇒ 1. Low Type ⇒ Bug Summary ⇒ Divide by zero error in /ansel/lib/Exif.php Queue ⇒ Ansel Milestone ⇒ Patch ⇒ Yes New Attachment: diff.txt State ⇒ Unconfirmed	Reply to this comment
There appears to be a bug in Exif.php where it doesn't check to see whether it's about to divide by zero when calculating the shutter speed. This patch fixes the issue in /ansel/lib/Exif.php.