1615308 - The "firefox.exe - Application Error" dialog is popped up when Compatibility mode is on

Status: VERIFIED FIXED

(Firefox :: Launcher Process, defect, P1)

Description

[Toshihito Kikuchi [:toshi]]

Attachment: c0000005.png

On Windows 10, if Compatibility mode for firefox.exe is set to Windows 7, the [firefox.exe - Application Error] dialog saying "The application was unable to start correctly (0xc0000005). Click OK to close the application." is popped up at startup.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Changing the priority to p1 as the bug is tracked by a release manager for the current beta.
See What Do You Triage for more information

Comment 2

[Toshihito Kikuchi [:toshi]]

Attachment: Bug 1615308 - Validate each entry of IAT for ntdll.dll before copying it into a new process. r=aklotz

We copy IAT for ntdll.dll into a new process so that our hook code can use
ntdll's functions even in the early stage. However, IAT can be modified and
some entries may point to an address which is not valid in the child process.
In such a case, we should not copy IAT. One example is Windows compat mode
which redirects some ntdll functions into AcLayers.dll via IAT.

With this patch, we verify each IAT entry and if any of them is outside ntdll,
we give up using the launcher process and start the browser process.

Comment 4

[Pascal Chevrel:pascalc]

Toshi, any news about your patch?

Comment 5

[Toshihito Kikuchi [:toshi]]

Aaron, did you have any chance to look at the change? Since this is P1 issue, if you have any cycles to review my patches, please take a look at this one first.

Comment 6

[(No longer employed by Mozilla) Aaron Klotz]

Reviewing today.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f080b12f030a
Validate each entry of IAT for ntdll.dll before copying it into a new process. r=aklotz

Comment 8

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/f080b12f030a

Comment 9

[abodenlosz]

Verified the fix with Firefox 75.0b2 on Windows 10 x86. The issue is no longer reproducible.

Comment 10

[Cristian Fogel [:cfogel]]

Awesome, thanks!