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Fix stack overflow when logging system encounters an error #8268

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merged 1 commit into from
Sep 7, 2020
Merged

Fix stack overflow when logging system encounters an error #8268

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Sep 7, 2020

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richvdh
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@richvdh richvdh commented Sep 7, 2020 •
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When stderr is redirected to a logger, it's possible to get into an infinite loop which results in a stack overflow if the logging system encounters an error.

Work around it by detecting the reentrant call and writing to the real stderr instead.

Fixes: #4202, #4240.

@richvdh richvdh force-pushed the rav/fix_stackoverflow_on_log_error branch from f273c76 to cc38965 Compare September 7, 2020 11:01
@richvdh richvdh requested a review from a team September 7, 2020 11:02
@richvdh richvdh merged commit 77794eb into develop Sep 7, 2020
@richvdh richvdh deleted the rav/fix_stackoverflow_on_log_error branch September 7, 2020 15:54
@richvdh richvdh mentioned this pull request Sep 7, 2020
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clokep
clokep reviewed Sep 8, 2020
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synapse/config/logger.py
# be redirected to /dev/null, but there's not much we can do)
try:
event_text = eventAsText(event)
print("logging during logging: %s" % event_text, file=sys.__stderr__)
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I think this was meant to be "error during logging", but I'm not sure?

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well, we don't know for sure it was an error. It could have been any other log level.

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Hmm... "logging during logging" doesn't really make sense to me though. What's that trying to say?

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while we were writing some logging, more logging happened.

I'm open to better wording :)

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Ah, I see what you're saying. Well...if nothing else that should be easy to find in the code-base if it ever comes up. 😄

richvdh added a commit that referenced this pull request Oct 1, 2020
@richvdh
Merge tag 'v1.21.0rc1' into develop
0b68577 
Synapse 1.21.0rc1 (2020-10-01)
==============================

Features
--------

- Require the user to confirm that their password should be reset after clicking the email confirmation link. ([\#8004](#8004))
- Add an admin API `GET /_synapse/admin/v1/event_reports` to read entries of table `event_reports`. Contributed by @dklimpel. ([\#8217](#8217))
- Consolidate the SSO error template across all configuration. ([\#8248](#8248), [\#8405](#8405))
- Add a configuration option to specify a whitelist of domains that a user can be redirected to after validating their email or phone number. ([\#8275](#8275), [\#8417](#8417))
- Add experimental support for sharding event persister. ([\#8294](#8294), [\#8387](#8387), [\#8396](#8396), [\#8419](#8419))
- Add the room topic and avatar to the room details admin API. ([\#8305](#8305))
- Add an admin API for querying rooms where a user is a member. Contributed by @dklimpel. ([\#8306](#8306))
- Add `uk.half-shot.msc2778.login.application_service` login type to allow appservices to login. ([\#8320](#8320))
- Add a configuration option that allows existing users to log in with OpenID Connect. Contributed by @BBBSnowball and @OmmyZhang. ([\#8345](#8345))
- Add prometheus metrics for replication requests. ([\#8406](#8406))
- Support passing additional single sign-on parameters to the client. ([\#8413](#8413))
- Add experimental reporting of metrics on expensive rooms for state-resolution. ([\#8420](#8420))
- Add experimental prometheus metric to track numbers of "large" rooms for state resolutiom. ([\#8425](#8425))
- Add prometheus metrics to track federation delays. ([\#8430](#8430))

Bugfixes
--------

- Fix a bug in the media repository where remote thumbnails with the same size but different crop methods would overwrite each other. Contributed by @deepbluev7. ([\#7124](#7124))
- Fix inconsistent handling of non-existent push rules, and stop tracking the `enabled` state of removed push rules. ([\#7796](#7796))
- Fix a longstanding bug when storing a media file with an empty `upload_name`. ([\#7905](#7905))
- Fix messages not being sent over federation until an event is sent into the same room. ([\#8230](#8230), [\#8247](#8247), [\#8258](#8258), [\#8272](#8272), [\#8322](#8322))
- Fix a longstanding bug where files that could not be thumbnailed would result in an Internal Server Error. ([\#8236](#8236), [\#8435](#8435))
- Upgrade minimum version of `canonicaljson` to version 1.4.0, to fix an unicode encoding issue. ([\#8262](#8262))
- Fix longstanding bug which could lead to incomplete database upgrades on SQLite. ([\#8265](#8265))
- Fix stack overflow when stderr is redirected to the logging system, and the logging system encounters an error. ([\#8268](#8268))
- Fix a bug which cause the logging system to report errors, if `DEBUG` was enabled and no `context` filter was applied. ([\#8278](#8278))
- Fix edge case where push could get delayed for a user until a later event was pushed. ([\#8287](#8287))
- Fix fetching malformed events from remote servers. ([\#8324](#8324))
- Fix `UnboundLocalError` from occuring when appservices send a malformed register request. ([\#8329](#8329))
- Don't send push notifications to expired user accounts. ([\#8353](#8353))
- Fix a regression in v1.19.0 with reactivating users through the admin API. ([\#8362](#8362))
- Fix a bug where during device registration the length of the device name wasn't limited. ([\#8364](#8364))
- Include `guest_access` in the fields that are checked for null bytes when updating `room_stats_state`. Broke in v1.7.2. ([\#8373](#8373))
- Fix theoretical race condition where events are not sent down `/sync` if the synchrotron worker is restarted without restarting other workers. ([\#8374](#8374))
- Fix a bug which could cause errors in rooms with malformed membership events, on servers using sqlite. ([\#8385](#8385))
- Fix "Re-starting finished log context" warning when receiving an event we already had over federation. ([\#8398](#8398))
- Fix incorrect handling of timeouts on outgoing HTTP requests. ([\#8400](#8400))
- Fix a regression in v1.20.0 in the `synapse_port_db` script regarding the `ui_auth_sessions_ips` table. ([\#8410](#8410))
- Remove unnecessary 3PID registration check when resetting password via an email address. Bug introduced in v0.34.0rc2. ([\#8414](#8414))

Improved Documentation
----------------------

- Add `/_synapse/client` to the reverse proxy documentation. ([\#8227](#8227))
- Add note to the reverse proxy settings documentation about disabling Apache's mod_security2. Contributed by Julian Fietkau (@jfietkau). ([\#8375](#8375))
- Improve description of `server_name` config option in `homserver.yaml`. ([\#8415](#8415))

Deprecations and Removals
-------------------------

- Drop support for `prometheus_client` older than 0.4.0. ([\#8426](#8426))

Internal Changes
----------------

- Fix tests on distros which disable TLSv1.0. Contributed by @danc86. ([\#8208](#8208))
- Simplify the distributor code to avoid unnecessary work. ([\#8216](#8216))
- Remove the `populate_stats_process_rooms_2` background job and restore functionality to `populate_stats_process_rooms`. ([\#8243](#8243))
- Clean up type hints for `PaginationConfig`. ([\#8250](#8250), [\#8282](#8282))
- Track the latest event for every destination and room for catch-up after federation outage. ([\#8256](#8256))
- Fix non-user visible bug in implementation of `MultiWriterIdGenerator.get_current_token_for_writer`. ([\#8257](#8257))
- Switch to the JSON implementation from the standard library. ([\#8259](#8259))
- Add type hints to `synapse.util.async_helpers`. ([\#8260](#8260))
- Simplify tests that mock asynchronous functions. ([\#8261](#8261))
- Add type hints to `StreamToken` and `RoomStreamToken` classes. ([\#8279](#8279))
- Change `StreamToken.room_key` to be a `RoomStreamToken` instance. ([\#8281](#8281))
- Refactor notifier code to correctly use the max event stream position. ([\#8288](#8288))
- Use slotted classes where possible. ([\#8296](#8296))
- Support testing the local Synapse checkout against the [Complement homeserver test suite](https://github.com/matrix-org/complement/). ([\#8317](#8317))
- Update outdated usages of `metaclass` to python 3 syntax. ([\#8326](#8326))
- Move lint-related dependencies to package-extra field, update CONTRIBUTING.md to utilise this. ([\#8330](#8330), [\#8377](#8377))
- Use the `admin_patterns` helper in additional locations. ([\#8331](#8331))
- Fix test logging to allow braces in log output. ([\#8335](#8335))
- Remove `__future__` imports related to Python 2 compatibility. ([\#8337](#8337))
- Simplify `super()` calls to Python 3 syntax. ([\#8344](#8344))
- Fix bad merge from `release-v1.20.0` branch to `develop`. ([\#8354](#8354))
- Factor out a `_send_dummy_event_for_room` method. ([\#8370](#8370))
- Improve logging of state resolution. ([\#8371](#8371))
- Add type annotations to `SimpleHttpClient`. ([\#8372](#8372))
- Refactor ID generators to use `async with` syntax. ([\#8383](#8383))
- Add `EventStreamPosition` type. ([\#8388](#8388))
- Create a mechanism for marking tests "logcontext clean". ([\#8399](#8399))
- A pair of tiny cleanups in the federation request code. ([\#8401](#8401))
- Add checks on startup that PostgreSQL sequences are consistent with their associated tables. ([\#8402](#8402))
- Do not include appservice users when calculating the total MAU for a server. ([\#8404](#8404))
- Typing fixes for `synapse.handlers.federation`. ([\#8422](#8422))
- Various refactors to simplify stream token handling. ([\#8423](#8423))
- Make stream token serializing/deserializing async. ([\#8427](#8427))
@richvdh richvdh mentioned this pull request Oct 2, 2020
Closed
netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this pull request Oct 17, 2020
@Midar
Update chat/matrix-synapse to 1.21.2
0582f7e 
Synapse 1.21.2 (2020-10-15)
===========================

Debian packages and Docker images have been rebuilt using the latest versions of dependency libraries, including authlib 0.15.1. Please see bugfixes below.

Security advisory
-----------------

* HTML pages served via Synapse were vulnerable to cross-site scripting (XSS)
  attacks. All server administrators are encouraged to upgrade.
  ([\#8444](matrix-org/synapse#8444))
  ([CVE-2020-26891](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-26891))

  This fix was originally included in v1.21.0 but was missing a security advisory.

  This was reported by [Denis Kasak](https://github.com/dkasak).

Bugfixes
--------

- Fix rare bug where sending an event would fail due to a racey assertion. ([\#8530](matrix-org/synapse#8530))
- An updated version of the authlib dependency is included in the Docker and Debian images to fix an issue using OpenID Connect. See [\#8534](matrix-org/synapse#8534) for details.


Synapse 1.21.1 (2020-10-13)
===========================

This release fixes a regression in v1.21.0 that prevented debian packages from being built.
It is otherwise identical to v1.21.0.

Synapse 1.21.0 (2020-10-12)
===========================

No significant changes since v1.21.0rc3.

As [noted in
v1.20.0](https://github.com/matrix-org/synapse/blob/release-v1.21.0/CHANGES.md#synapse-1200-2020-09-22),
a future release will drop support for accessing Synapse's
[Admin API](https://github.com/matrix-org/synapse/tree/master/docs/admin_api) under the
`/_matrix/client/*` endpoint prefixes. At that point, the Admin API will only
be accessible under `/_synapse/admin`.


Synapse 1.21.0rc3 (2020-10-08)
==============================

Bugfixes
--------

- Fix duplication of events on high traffic servers, caused by PostgreSQL `could not serialize access due to concurrent update` errors. ([\#8456](matrix-org/synapse#8456))


Internal Changes
----------------

- Add Groovy Gorilla to the list of distributions we build `.deb`s for. ([\#8475](matrix-org/synapse#8475))


Synapse 1.21.0rc2 (2020-10-02)
==============================

Features
--------

- Convert additional templates from inline HTML to Jinja2 templates. ([\#8444](matrix-org/synapse#8444))

Bugfixes
--------

- Fix a regression in v1.21.0rc1 which broke thumbnails of remote media. ([\#8438](matrix-org/synapse#8438))
- Do not expose the experimental `uk.half-shot.msc2778.login.application_service` flow in the login API, which caused a compatibility problem with Element iOS. ([\#8440](matrix-org/synapse#8440))
- Fix malformed log line in new federation "catch up" logic. ([\#8442](matrix-org/synapse#8442))
- Fix DB query on startup for negative streams which caused long start up times. Introduced in [\#8374](matrix-org/synapse#8374). ([\#8447](matrix-org/synapse#8447))


Synapse 1.21.0rc1 (2020-10-01)
==============================

Features
--------

- Require the user to confirm that their password should be reset after clicking the email confirmation link. ([\#8004](matrix-org/synapse#8004))
- Add an admin API `GET /_synapse/admin/v1/event_reports` to read entries of table `event_reports`. Contributed by @dklimpel. ([\#8217](matrix-org/synapse#8217))
- Consolidate the SSO error template across all configuration. ([\#8248](matrix-org/synapse#8248), [\#8405](matrix-org/synapse#8405))
- Add a configuration option to specify a whitelist of domains that a user can be redirected to after validating their email or phone number. ([\#8275](matrix-org/synapse#8275), [\#8417](matrix-org/synapse#8417))
- Add experimental support for sharding event persister. ([\#8294](matrix-org/synapse#8294), [\#8387](matrix-org/synapse#8387), [\#8396](matrix-org/synapse#8396), [\#8419](matrix-org/synapse#8419))
- Add the room topic and avatar to the room details admin API. ([\#8305](matrix-org/synapse#8305))
- Add an admin API for querying rooms where a user is a member. Contributed by @dklimpel. ([\#8306](matrix-org/synapse#8306))
- Add `uk.half-shot.msc2778.login.application_service` login type to allow appservices to login. ([\#8320](matrix-org/synapse#8320))
- Add a configuration option that allows existing users to log in with OpenID Connect. Contributed by @BBBSnowball and @OmmyZhang. ([\#8345](matrix-org/synapse#8345))
- Add prometheus metrics for replication requests. ([\#8406](matrix-org/synapse#8406))
- Support passing additional single sign-on parameters to the client. ([\#8413](matrix-org/synapse#8413))
- Add experimental reporting of metrics on expensive rooms for state-resolution. ([\#8420](matrix-org/synapse#8420))
- Add experimental prometheus metric to track numbers of "large" rooms for state resolutiom. ([\#8425](matrix-org/synapse#8425))
- Add prometheus metrics to track federation delays. ([\#8430](matrix-org/synapse#8430))


Bugfixes
--------

- Fix a bug in the media repository where remote thumbnails with the same size but different crop methods would overwrite each other. Contributed by @deepbluev7. ([\#7124](matrix-org/synapse#7124))
- Fix inconsistent handling of non-existent push rules, and stop tracking the `enabled` state of removed push rules. ([\#7796](matrix-org/synapse#7796))
- Fix a longstanding bug when storing a media file with an empty `upload_name`. ([\#7905](matrix-org/synapse#7905))
- Fix messages not being sent over federation until an event is sent into the same room. ([\#8230](matrix-org/synapse#8230), [\#8247](matrix-org/synapse#8247), [\#8258](matrix-org/synapse#8258), [\#8272](matrix-org/synapse#8272), [\#8322](matrix-org/synapse#8322))
- Fix a longstanding bug where files that could not be thumbnailed would result in an Internal Server Error. ([\#8236](matrix-org/synapse#8236), [\#8435](matrix-org/synapse#8435))
- Upgrade minimum version of `canonicaljson` to version 1.4.0, to fix an unicode encoding issue. ([\#8262](matrix-org/synapse#8262))
- Fix longstanding bug which could lead to incomplete database upgrades on SQLite. ([\#8265](matrix-org/synapse#8265))
- Fix stack overflow when stderr is redirected to the logging system, and the logging system encounters an error. ([\#8268](matrix-org/synapse#8268))
- Fix a bug which cause the logging system to report errors, if `DEBUG` was enabled and no `context` filter was applied. ([\#8278](matrix-org/synapse#8278))
- Fix edge case where push could get delayed for a user until a later event was pushed. ([\#8287](matrix-org/synapse#8287))
- Fix fetching malformed events from remote servers. ([\#8324](matrix-org/synapse#8324))
- Fix `UnboundLocalError` from occuring when appservices send a malformed register request. ([\#8329](matrix-org/synapse#8329))
- Don't send push notifications to expired user accounts. ([\#8353](matrix-org/synapse#8353))
- Fix a regression in v1.19.0 with reactivating users through the admin API. ([\#8362](matrix-org/synapse#8362))
- Fix a bug where during device registration the length of the device name wasn't limited. ([\#8364](matrix-org/synapse#8364))
- Include `guest_access` in the fields that are checked for null bytes when updating `room_stats_state`. Broke in v1.7.2. ([\#8373](matrix-org/synapse#8373))
- Fix theoretical race condition where events are not sent down `/sync` if the synchrotron worker is restarted without restarting other workers. ([\#8374](matrix-org/synapse#8374))
- Fix a bug which could cause errors in rooms with malformed membership events, on servers using sqlite. ([\#8385](matrix-org/synapse#8385))
- Fix "Re-starting finished log context" warning when receiving an event we already had over federation. ([\#8398](matrix-org/synapse#8398))
- Fix incorrect handling of timeouts on outgoing HTTP requests. ([\#8400](matrix-org/synapse#8400))
- Fix a regression in v1.20.0 in the `synapse_port_db` script regarding the `ui_auth_sessions_ips` table. ([\#8410](matrix-org/synapse#8410))
- Remove unnecessary 3PID registration check when resetting password via an email address. Bug introduced in v0.34.0rc2. ([\#8414](matrix-org/synapse#8414))


Improved Documentation
----------------------

- Add `/_synapse/client` to the reverse proxy documentation. ([\#8227](matrix-org/synapse#8227))
- Add note to the reverse proxy settings documentation about disabling Apache's mod_security2. Contributed by Julian Fietkau (@jfietkau). ([\#8375](matrix-org/synapse#8375))
- Improve description of `server_name` config option in `homserver.yaml`. ([\#8415](matrix-org/synapse#8415))


Deprecations and Removals
-------------------------

- Drop support for `prometheus_client` older than 0.4.0. ([\#8426](matrix-org/synapse#8426))


Internal Changes
----------------

- Fix tests on distros which disable TLSv1.0. Contributed by @danc86. ([\#8208](matrix-org/synapse#8208))
- Simplify the distributor code to avoid unnecessary work. ([\#8216](matrix-org/synapse#8216))
- Remove the `populate_stats_process_rooms_2` background job and restore functionality to `populate_stats_process_rooms`. ([\#8243](matrix-org/synapse#8243))
- Clean up type hints for `PaginationConfig`. ([\#8250](matrix-org/synapse#8250), [\#8282](matrix-org/synapse#8282))
- Track the latest event for every destination and room for catch-up after federation outage. ([\#8256](matrix-org/synapse#8256))
- Fix non-user visible bug in implementation of `MultiWriterIdGenerator.get_current_token_for_writer`. ([\#8257](matrix-org/synapse#8257))
- Switch to the JSON implementation from the standard library. ([\#8259](matrix-org/synapse#8259))
- Add type hints to `synapse.util.async_helpers`. ([\#8260](matrix-org/synapse#8260))
- Simplify tests that mock asynchronous functions. ([\#8261](matrix-org/synapse#8261))
- Add type hints to `StreamToken` and `RoomStreamToken` classes. ([\#8279](matrix-org/synapse#8279))
- Change `StreamToken.room_key` to be a `RoomStreamToken` instance. ([\#8281](matrix-org/synapse#8281))
- Refactor notifier code to correctly use the max event stream position. ([\#8288](matrix-org/synapse#8288))
- Use slotted classes where possible. ([\#8296](matrix-org/synapse#8296))
- Support testing the local Synapse checkout against the [Complement homeserver test suite](https://github.com/matrix-org/complement/). ([\#8317](matrix-org/synapse#8317))
- Update outdated usages of `metaclass` to python 3 syntax. ([\#8326](matrix-org/synapse#8326))
- Move lint-related dependencies to package-extra field, update CONTRIBUTING.md to utilise this. ([\#8330](matrix-org/synapse#8330), [\#8377](matrix-org/synapse#8377))
- Use the `admin_patterns` helper in additional locations. ([\#8331](matrix-org/synapse#8331))
- Fix test logging to allow braces in log output. ([\#8335](matrix-org/synapse#8335))
- Remove `__future__` imports related to Python 2 compatibility. ([\#8337](matrix-org/synapse#8337))
- Simplify `super()` calls to Python 3 syntax. ([\#8344](matrix-org/synapse#8344))
- Fix bad merge from `release-v1.20.0` branch to `develop`. ([\#8354](matrix-org/synapse#8354))
- Factor out a `_send_dummy_event_for_room` method. ([\#8370](matrix-org/synapse#8370))
- Improve logging of state resolution. ([\#8371](matrix-org/synapse#8371))
- Add type annotations to `SimpleHttpClient`. ([\#8372](matrix-org/synapse#8372))
- Refactor ID generators to use `async with` syntax. ([\#8383](matrix-org/synapse#8383))
- Add `EventStreamPosition` type. ([\#8388](matrix-org/synapse#8388))
- Create a mechanism for marking tests "logcontext clean". ([\#8399](matrix-org/synapse#8399))
- A pair of tiny cleanups in the federation request code. ([\#8401](matrix-org/synapse#8401))
- Add checks on startup that PostgreSQL sequences are consistent with their associated tables. ([\#8402](matrix-org/synapse#8402))
- Do not include appservice users when calculating the total MAU for a server. ([\#8404](matrix-org/synapse#8404))
- Typing fixes for `synapse.handlers.federation`. ([\#8422](matrix-org/synapse#8422))
- Various refactors to simplify stream token handling. ([\#8423](matrix-org/synapse#8423))
- Make stream token serializing/deserializing async. ([\#8427](matrix-org/synapse#8427))
@richvdh richvdh mentioned this pull request Jun 10, 2021
Open
babolivier pushed a commit that referenced this pull request Sep 1, 2021
@anoadragon453
Merge commit '77794ebc7' into anoa/dinsic_release_1_21_x
4fd0129 
* commit '77794ebc7':
  Fix stack overflow when logging system encounters an error (#8268)
richvdh added a commit that referenced this pull request Apr 29, 2022
@richvdh
Remove special-case for twisted logger
8471ca3 
This was originally added when we first added a `MemoryHandler` to the default
log config back in #8040, to ensure
that we didn't explode with an infinite loop if there was an error formatting
the logs.

Since then, we made additional improvements to logging which make this
workaround redundant. In particular:

 * we no longer attempt to log un-UTF8-decodable byte sequences, which were the
   most likely cause of an error in the first place.

 * #8268 ensures that in the unlikely
   case that there *is* an error, it won't cause an infinite loop.
@richvdh richvdh mentioned this pull request Apr 29, 2022
Merged
richvdh added a commit that referenced this pull request Apr 29, 2022
@richvdh
Remove special-case for twisted logger (#12589)
8d156ec 
This was originally added when we first added a `MemoryHandler` to the default
log config back in #8040, to ensure
that we didn't explode with an infinite loop if there was an error formatting
the logs.

Since then, we made additional improvements to logging which make this
workaround redundant. In particular:

 * we no longer attempt to log un-UTF8-decodable byte sequences, which were the
   most likely cause of an error in the first place.

 * #8268 ensures that in the unlikely
   case that there *is* an error, it won't cause an infinite loop.
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