1582776 - FuncHookCrossProcess should not store the child process's stub function in mOrigFunc

Status: RESOLVED FIXED

(Core :: mozglue, defect)

Description

[(No longer employed by Mozilla) Aaron Klotz]

This is showing up with hooks that are set both by the launcher process and by the browser process when starting early DLL blocklist init on content processes:

• The browser's copy of mOrigFunc was set by the launcher process.
• The browser is setting a hook in the new child process, which writes to the child's mOrigFunc.
• But FuncHookCrossProcess also writes that pointer to the browser's mOrigFunc, thus corrupting the browser process's copy of the pointer.

For in-process hooks, we want to immediately write the stub pointer to its final location; this is not an issue for cross-process hooks since the child process is suspended when we do this and the parent process can't call the stub; there is no possibility of a race.

Comment 1

[(No longer employed by Mozilla) Aaron Klotz]

Attachment: Bug 1582776: Change cross-process stub to not store remote stub pointer in local mOrigFunc; r=handyman!

This is showing up with hooks that are set both by the launcher process and by
the browser process when starting early DLL blocklist init on content processes:

• The browser's copy of mOrigFunc was set by the launcher process.
• The browser is setting a hook in the new child process, which writes to the
  child's mOrigFunc.
• But FuncHookCrossProcess also writes that pointer to the browser's mOrigFunc,
  thus corrupting the browser process's copy of the pointer.

For in-process hooks, we want to immediately write the stub pointer to its final
location; this is not an issue for cross-process hooks since the child process
is suspended when we do this and the parent process can't call the stub; there
is no possibility of a race.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/de034010ab47
Change cross-process stub to not store remote stub pointer in local mOrigFunc; r=handyman

Comment 3

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/de034010ab47