[20.10 backport] daemon/logger: read the length header correctly #43165
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Before this change, if Decode() couldn't read a log record fully, the subsequent invocation of Decode() would read the record's non-header part as a header and cause a huge heap allocation. This change prevents such a case by having the intermediate buffer in the decoder struct. Fixes moby#42125. Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com> (cherry picked from commit 48d387a) Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com> (cherry picked from commit f2e458e) Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
followLogs() is getting really long (170+ lines) and complex.
The function has multiple inner functions that mutate its variables.
To refactor the function, this change introduces follow{} struct.
The inner functions are now defined as ordinal methods, which are
accessible from tests.
Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>
(cherry picked from commit 7a10f5a)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com> (cherry picked from commit c91e09b) Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
thaJeztah
added
area/logging
status/2-code-review
impact/changelog
kind/bugfix
|
@cpuguy83 @samuelkarp ptal |
samuelkarp
approved these changes
Jan 27, 2022
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fixes #42125
Backport of:
Before this change, if Decode() couldn't read a log record fully,
the subsequent invocation of Decode() would read the record's non-header part
as a header and cause a huge heap allocation.
This change prevents such a case by having the intermediate buffer in
the decoder struct.
Fixes #42125.
- What I did
Changing decoder struct to fix #42125.
- How I did it
Changing decoder struct to keep read-but-unused bytes.
- How to verify it
Run
docker logs -f $(docker run --rm -d --log-driver local alpine cat /dev/urandom) > /dev/null. It kills dockerd after a few minutes before the change.- Description for the changelog
- A picture of a cute animal (not mandatory but encouraged)
(from https://www.zooborns.com/zooborns/2021/05/two-very-different-babies-emerge-at-woodland-park-zoo.html)