1751012 - Writing to stdout/stderr in content process should not return error

Status: RESOLVED FIXED

(Core :: Security: Process Sandboxing, defect, P3)

Description

[Chris Martin [:cmartin]]

In Rust's implementation of stdio, this code exists:

if let Err(e) = global_s().write_fmt(args) {
  panic!("failed printing to {}: {}", label, e);
}

This means that if Rust fails to write to stdout in WebRender (like it does here), it will crash with the following error:

failed printing to stdout: Access is denied. (os error 5)

Comment 1

[Chris Martin [:cmartin]]

Attachment: Bug 1751012 - Don't print to stdout in WebRender

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d9d0b0a46f7d
Don't print to stdout in WebRender r=kvark

Comment 3

[Atila Butkovits]

Backed out for causing build bustages

Backout link: https://hg.mozilla.org/integration/autoland/rev/55a08c98015b714e4302b50075cb9917e146b375

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=d9d0b0a46f7d6ea22f10fa8dfaf3fe3b79769e14&selectedTaskRun=KN6tCzOqRG2FPQeOFuTouA.0

Failure log:
-https://treeherder.mozilla.org/logviewer?job_id=364832746&repo=autoland&lineNumber=65209

Comment 4

[Chris Martin [:cmartin]]

After our last team meeting, Nika brought up the good point that sooner-or-later we are going to end up in a situation where Rust code that we don't control will print to stdout/stderr, which will trigger a panic with the current Win32k Lockdown behavior.

It seems like we are going to have to find a way to make writing to stdout/stderr in content not return an error code, even if all it does is yeet the string into the void.

Comment 5

[Chris Martin [:cmartin]]

It appears that it's not actually specific to Win32k Lockdown but instead to Windows 8.1 (And possibly others?)

Lowering priority, since it's no longer blocking Win32k Lockdown and afaict it only affects debug builds.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f7cb0735536c
Don't print to stdout in WebRender r=kvark

Comment 7

[Noemi Erli[:noemi_erli]]

https://hg.mozilla.org/mozilla-central/rev/f7cb0735536c