Conversation
jann@infosec.exchange

Jann Horn

The combination of Linux stable backports and not having explicitly documented and enforced API contracts is so annoying.
Write a bugfix that uses an existing helper function that can return error type A. Your bugfix gets backported to an old kernel. Surprise, in the old kernel, the helper function can also return error type B. And suddenly your bugfix causes more breakage.

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brauner@mastodon.social

Christian Brauner 🦊🐺

Reply to @jann@infosec.exchange

@jann for another variant look at my fix for binfmt_misc to not leak the userns. See the comment beneath the patch.

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gregkh

Greg K-H

Reply to @brauner@mastodon.social
@brauner @jann I appreciate the comment, but as I will only see the changelog that shows up in Linus's tree, that's going to be a mess. Perhaps just set the Fixes: tag to not point to older trees and then send backports when needed?
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brauner@mastodon.social

Christian Brauner 🦊🐺

Reply to @gregkh

@gregkh @jann I happily do whatever makes stable maintenance easiest but I simply had no idea what to do here.

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jmorris

James Morris

Reply to @jann@infosec.exchange
Edited 4 days ago
@jann this is why some companies have teams of people who do little except manually review every kernel security fix and related backport across their product matrices. At some point I hope the industry sees more value in addressing some of the underlying issues, well left of boom.
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vbabka@mastodon.social

Vlastimil Babka 🇨🇿🇪🇺🇺🇦

Reply to @gregkh

@gregkh @jann @brauner can there be a way that doesn't require mangling Fixes: to something not technically true? E.g. Cc: stable@v.k.o # 6.12+ only unless specific backport provided

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