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worker: fix race condition in node_messaging.cc #33429

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worker: fix race condition in node_messaging.cc #33429

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@addaleax addaleax commented May 16, 2020 •
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AddToIncomingQueue() relies on owner_ only being modified with
mutex_ being locked, but in these two places, that didn’t happen.

Modify them to use Detach() instead, which has the same effect
as setting owner_ = nullptr here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in AddToIncomingQueue() when compiling with
optimizations enabled.

(The other side of the race condition happens here:

node/src/node_messaging.cc

Lines 430 to 433 in 48b1595

if (owner_ != nullptr) {
Debug(owner_, "Adding message to incoming queue");
owner_->TriggerAsync();
}

)

Checklist
  • make -j4 test (UNIX), or vcbuild test (Windows) passes
  • commit message follows commit guidelines

@nodejs-github-bot nodejs-github-bot added the c++ Issues and PRs that require attention from people who are familiar with C++. label May 16, 2020
@addaleax
worker: fix race condition in node_messaging.cc
4f144eb 
`AddToIncomingQueue()` relies on `owner_` only being modified with
`mutex_` being locked, but in these two places, that didn’t happen.

Modify them to use `Detach()` instead, which has the same effect
as setting `owner_ = nullptr` here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in `AddToIncomingQueue()` when compiling with
optimizations enabled.
@addaleax addaleax force-pushed the worker-messageport-owner-double-load branch from 4895d3a to 4f144eb Compare May 16, 2020 10:12
@addaleax addaleax mentioned this pull request May 16, 2020
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CI: https://ci.nodejs.org/job/node-test-pull-request/31356/

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CI: https://ci.nodejs.org/job/node-test-pull-request/31359/

@addaleax addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label May 19, 2020
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CI: https://ci.nodejs.org/job/node-test-pull-request/31424/

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Landed in 0e92ae6

@addaleax addaleax closed this May 19, 2020
addaleax added a commit that referenced this pull request May 19, 2020
@addaleax
worker: fix race condition in node_messaging.cc
0e92ae6 
`AddToIncomingQueue()` relies on `owner_` only being modified with
`mutex_` being locked, but in these two places, that didn’t happen.

Modify them to use `Detach()` instead, which has the same effect
as setting `owner_ = nullptr` here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in `AddToIncomingQueue()` when compiling with
optimizations enabled.

PR-URL: #33429
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: James M Snell <[email protected]>
@addaleax addaleax deleted the worker-messageport-owner-double-load branch May 19, 2020 21:57
codebytere pushed a commit that referenced this pull request May 21, 2020
@addaleax @codebytere
worker: fix race condition in node_messaging.cc
3a3eb84 
`AddToIncomingQueue()` relies on `owner_` only being modified with
`mutex_` being locked, but in these two places, that didn’t happen.

Modify them to use `Detach()` instead, which has the same effect
as setting `owner_ = nullptr` here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in `AddToIncomingQueue()` when compiling with
optimizations enabled.

PR-URL: #33429
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: James M Snell <[email protected]>
codebytere pushed a commit that referenced this pull request Jun 7, 2020
@addaleax @codebytere
worker: fix race condition in node_messaging.cc
4776746 
`AddToIncomingQueue()` relies on `owner_` only being modified with
`mutex_` being locked, but in these two places, that didn’t happen.

Modify them to use `Detach()` instead, which has the same effect
as setting `owner_ = nullptr` here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in `AddToIncomingQueue()` when compiling with
optimizations enabled.

PR-URL: #33429
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: James M Snell <[email protected]>
codebytere pushed a commit that referenced this pull request Jun 9, 2020
@addaleax @codebytere
worker: fix race condition in node_messaging.cc
5eed20b 
`AddToIncomingQueue()` relies on `owner_` only being modified with
`mutex_` being locked, but in these two places, that didn’t happen.

Modify them to use `Detach()` instead, which has the same effect
as setting `owner_ = nullptr` here, but does it with proper locking.

This race condition probably only shows up in practice when Node.js
is compiled in debug mode, because the compiler eliminates the
duplicate load in `AddToIncomingQueue()` when compiling with
optimizations enabled.

PR-URL: #33429
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: David Carlier <[email protected]>
Reviewed-By: James M Snell <[email protected]>
@codebytere codebytere mentioned this pull request Jun 9, 2020
Merged
@codebytere codebytere mentioned this pull request Jun 28, 2020
Merged
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@devnexen devnexen devnexen approved these changes

@cjihrig cjihrig cjihrig approved these changes

@jasnell jasnell jasnell approved these changes

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