src: do not unnecessarily re-assign uv handle data #31696

addaleax · 2020-02-08T16:06:34Z

a555be2 re-assigned async_.data to indicate success
or failure of the constructor. As the HandleWrap implementation
uses that field to access the HandleWrap instance from the
libuv handle, this introduced two issues:

It implicitly assumed that casting
MessagePort* → void* → HandleWrap* would be valid.
It made the HandleWrap::OnClose() function fail with a
nullptr dereference if the constructor did fail.

In particular, the second issue made
test/parallel/test-worker-cleanexit-with-moduleload.js crash at
least once in CI.

Since re-assigning async_.data isn’t actually necessary here
(only a leftover from earlier versions of that commit), fix this by
using a local variable instead, and add a CHECK that provides better
error messages for this type of issue in the future.

Refs: #31605

Example failure: https://ci.nodejs.org/job/node-test-commit-linux-containered/17944/nodes=ubuntu1804_sharedlibs_openssl111_x64/testReport/junit/(root)/test/parallel_test_worker_cleanexit_with_moduleload/

Checklist

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

a555be2 re-assigned `async_.data` to indicate success or failure of the constructor. As the `HandleWrap` implementation uses that field to access the `HandleWrap` instance from the libuv handle, this introduced two issues: - It implicitly assumed that casting `MessagePort*` → `void*` → `HandleWrap*` would be valid. - It made the `HandleWrap::OnClose()` function fail with a `nullptr` dereference if the constructor did fail. In particular, the second issue made test/parallel/test-worker-cleanexit-with-moduleload.js` crash at least once in CI. Since re-assigning `async_.data` isn’t actually necessary here (only a leftover from earlier versions of that commit), fix this by using a local variable instead, and add a `CHECK` that provides better error messages for this type of issue in the future. Refs: nodejs#31605

nodejs-github-bot · 2020-02-08T16:09:16Z

CI: https://ci.nodejs.org/job/node-test-pull-request/29022/

nodejs-github-bot · 2020-02-08T17:41:49Z

CI: https://ci.nodejs.org/job/node-test-pull-request/29024/ (:white_check_mark:)

addaleax · 2020-02-10T16:29:30Z

Landed in f938cbd

a555be2 re-assigned `async_.data` to indicate success or failure of the constructor. As the `HandleWrap` implementation uses that field to access the `HandleWrap` instance from the libuv handle, this introduced two issues: - It implicitly assumed that casting `MessagePort*` → `void*` → `HandleWrap*` would be valid. - It made the `HandleWrap::OnClose()` function fail with a `nullptr` dereference if the constructor did fail. In particular, the second issue made test/parallel/test-worker-cleanexit-with-moduleload.js` crash at least once in CI. Since re-assigning `async_.data` isn’t actually necessary here (only a leftover from earlier versions of that commit), fix this by using a local variable instead, and add a `CHECK` that provides better error messages for this type of issue in the future. Refs: #31605 PR-URL: #31696 Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

codebytere · 2020-03-15T16:20:36Z

@addaleax if this is something that should be in v12.x, could you please backport it there? There are a nest of conflicts and i want to be extra careful 😅

a555be2 re-assigned `async_.data` to indicate success or failure of the constructor. As the `HandleWrap` implementation uses that field to access the `HandleWrap` instance from the libuv handle, this introduced two issues: - It implicitly assumed that casting `MessagePort*` → `void*` → `HandleWrap*` would be valid. - It made the `HandleWrap::OnClose()` function fail with a `nullptr` dereference if the constructor did fail. In particular, the second issue made test/parallel/test-worker-cleanexit-with-moduleload.js` crash at least once in CI. Since re-assigning `async_.data` isn’t actually necessary here (only a leftover from earlier versions of that commit), fix this by using a local variable instead, and add a `CHECK` that provides better error messages for this type of issue in the future. Refs: nodejs#31605 PR-URL: nodejs#31696 Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

a555be2 re-assigned `async_.data` to indicate success or failure of the constructor. As the `HandleWrap` implementation uses that field to access the `HandleWrap` instance from the libuv handle, this introduced two issues: - It implicitly assumed that casting `MessagePort*` → `void*` → `HandleWrap*` would be valid. - It made the `HandleWrap::OnClose()` function fail with a `nullptr` dereference if the constructor did fail. In particular, the second issue made test/parallel/test-worker-cleanexit-with-moduleload.js` crash at least once in CI. Since re-assigning `async_.data` isn’t actually necessary here (only a leftover from earlier versions of that commit), fix this by using a local variable instead, and add a `CHECK` that provides better error messages for this type of issue in the future. Refs: #31605 PR-URL: #31696 Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com> Reviewed-By: David Carlier <devnexen@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

addaleax · 2020-04-28T16:23:06Z

@targos … this seems to have ended up on v12.x-staging before the v12.16.3 release, but not in the release itself. It fixes a segfault that is now occurring with v12.16.3 – is there anything I could have done differently here to prevent that?

(I do know that I kind of dropped the ball on backporting this, but as you noticed, that was only necessary because other commits hadn’t landed yet, so I don’t think it would have made a difference?)

targos · 2020-04-28T17:03:10Z

@addaleax this wasn't on v12.x-staging before the release. I just updated the branch right after it.

is there anything I could have done differently here to prevent that?

I think the most reliable way would have been to label the original PR as backport-requested with a message indicating that it had to land with this one.

I'm definitely open to other ideas. The real issue is that we don't have a documented and easy way to express relations between pull requests.

addaleax · 2020-04-28T18:43:41Z

@targos Yeah, I’d be a fan of having something more specific than Refs:, e.g. Must-Be-Released-With: <pr-url> that would indicate that PRs should have to land together… I’ll put this on my list of things that I can try to implement

nodejs-github-bot added the c++ Issues and PRs that require attention from people who are familiar with C++. label Feb 8, 2020

addaleax added the worker Issues and PRs related to Worker support. label Feb 8, 2020

santigimeno approved these changes Feb 8, 2020

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addaleax added the author ready PRs that have at least one approval, no pending requests for changes, and a CI started. label Feb 8, 2020

cjihrig approved these changes Feb 9, 2020

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jasnell approved these changes Feb 10, 2020

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addaleax closed this Feb 10, 2020

addaleax deleted the fix-messageport-dtor branch February 10, 2020 16:29

codebytere mentioned this pull request Feb 17, 2020

v13.9.0 proposal #31837

Merged

codebytere added the backport-requested-v12.x label Mar 15, 2020

targos removed author ready PRs that have at least one approval, no pending requests for changes, and a CI started. backport-requested-v12.x labels Apr 25, 2020

targos mentioned this pull request May 2, 2020

v12.17.0 release proposal #33197

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src: do not unnecessarily re-assign uv handle data #31696

src: do not unnecessarily re-assign uv handle data #31696

addaleax commented Feb 8, 2020 •

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src: do not unnecessarily re-assign uv handle data #31696

src: do not unnecessarily re-assign uv handle data #31696

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