1829125 - PHC area should be aligned to and a multiple of the jemalloc chunk size

Status: RESOLVED FIXED

(Core :: Memory Allocator, task)

Description

[Paul Bone [:pbone]]

If jemalloc tries to free an invalid pointer but one that is NOT a PHC pointer the address calculations performed by jemalloc could cause jemalloc to dereference a PHC pointer, adding PHC stacks to a crash report that could be a red herring.

If we size & align the PHC area it could reduce the chance of jemalloc or JS GC's address calculations from causing a PHC pointer to be dereferenced.

It seems far fetched but we think this has happened at least once.

Comment 1

[Paul Bone [:pbone]]

Attachment: Bug 1829125 - PHC area is a multiple of the jemalloc/JSGC chunk size r=glandium

Comment 2

[Paul Bone [:pbone]]

Attachment: Bug 1829125 - Export aligned page allocation from mozjemalloc r=glandium

Depends on D178029

Comment 3

[Paul Bone [:pbone]]

Attachment: Bug 1829125 - Use algned page allocation in PHC r=glandium

Depends on D178030

Comment 4

[Paul Bone [:pbone]]

Hi Glandium,

I've posted these patches for review, but I want to ask: I'm passing the pages_map and pages_umnap functions as parameters, would you prefer templates?

Comment 5

[Paul Bone [:pbone]]

My question is no-longer relevant.

Comment 6

[Paul Bone [:pbone]]

Attachment: Bug 1829125 - Align the PHC area to the jemalloc chunk size r=glandium

Depends on D178029

Comment 7

[Paul Bone [:pbone]]

Attachment: Bug 1829125 - Add a PHCExhaustion test r=glandium

Depends on D181422

Comment 8

[Paul Bone [:pbone]]

We can land this after the soft code freeze.

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0ad1e4859c59
Add a PHCExhaustion test r=glandium
https://hg.mozilla.org/integration/autoland/rev/6308011c6366
Align the PHC area to the jemalloc chunk size r=glandium

Comment 10

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/0ad1e4859c59
https://hg.mozilla.org/mozilla-central/rev/6308011c6366