1482883 - Firefox crashes while re-arranging tabs after specific steps

Status: REOPENED

(Firefox for iOS :: General, defect, P3)

Description

[Simon Basca [:SimonB]]

Attachment: Client-2018-08-13-163814.ips.beta

Build: 13.1 (11724) 
Device: iPhone 8
iOS: 11.4

Pre-conditions:
- Have a few open tabs

Steps to reproduce:
1. Go to tabs tray
2. Long press on a tab
3. Drag it around to re-arrange (do not release the finger)
4. While holding the finger on the tab, press the home button to background firefox
5. Restore Firefox
6. From tabs tray try to drag the same tab

Actual results:
- Firefox crashes. 

Video:
- https://www.youtube.com/watch?v=3JmgQYaRBgg

Comment 1

[damian.stanczyk]

Attachment: Pull request

Got 100% reproduction rate:
precondition: 5 opened tabs
- select tab [4] (one before last )
- long hold on last tab [5]
- go for first tab postion, do not release the tab
- press home
- go back to app and select first tab - crash

Comment 2

[Simon Basca [:SimonB]]

Found steps to reproduce this issue which can fit in a more use case scenario:

1. Have a few Tabs opened to enable scrolling in Tabs Tray (I have ~20) 
2. Long tap on the last tab to re-arrange
3. Long tap on the tab to drag the tab to the top (I usually use the other hand to scroll faster in tabs tray)
4. Using the other hand, swipe down to scroll up
5. If the notifications center is revealed accidentally, the tabs re-order will be interrupted
6. Trying again to re-order the tabs will crash firefox

Here is a video: 
- https://www.youtube.com/watch?v=Xs2Gx6413A0

Comment 3

[Simon Basca [:SimonB]]

I am still reproducing this issue after following all the steps from the description, comment #1 and comment #2.

Comment 4

[Simon Basca [:SimonB]]

Looks like this patch is fixing Bug 1483852. See https://bugzilla.mozilla.org/show_bug.cgi?id=1483852#c2.