{"id":2745,"date":"2026-04-14T14:55:52","date_gmt":"2026-04-14T20:55:52","guid":{"rendered":"https:\/\/embeddedor.com\/blog\/?p=2745"},"modified":"2026-04-23T11:00:36","modified_gmt":"2026-04-23T17:00:36","slug":"100-wflex-array-member-not-at-end-issues-in-linux-next","status":"publish","type":"post","link":"https:\/\/embeddedor.com\/blog\/2026\/04\/14\/100-wflex-array-member-not-at-end-issues-in-linux-next\/","title":{"rendered":"100 -Wflex-array-member-not-at-end issues in linux-next"},"content":{"rendered":"\n
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Today I woke up to the great news that we now have “only” 100 -Wflex-array-member-not-at-end<\/code> issues left to be addressed in linux-next.<\/code> I started fixing these issues a couple of years ago after running into a memory corruption bug1<\/a><\/sup> caused by a flexible-array member in the middle of a structure.<\/p>\n\n\n\n

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I discovered this bug while reviewing my slides a couple of days before presenting at Kernel Recipes 2023 in Paris 🇫🇷. Naturally, I didn’t miss the opportunity to share the story during my presentation2<\/a><\/sup> and talk about my plans to enable this compiler option upstream.<\/p>\n\n\n\n

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A few months before Kernel Recipes that year, I had experimented a bit with the, at the time, under-development version of -Wflex-array-member-not-at-end.<\/code> Honestly, given the number of warnings and issues reported by the compiler, I didn’t pay much attention to it at the time. However, I knew it would eventually become one of the next great challenges to tackle in the Linux Kernel Self-Protection Project3<\/a><\/sup>.<\/p>\n\n\n\n

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It wasn’t until I confirmed that the bug I had incidentally found while reviewing my slides was also reported by -Wflex-array-member-not-at-end<\/code> that I began actively addressing these issues and thinking about how to solve the problem as a whole.<\/p>\n\n\n\n

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In a future post, I’ll dive deeper into the effort and innovations behind this work, but for now I’ll just say that I’m really happy that about 85% of it is complete<\/strong>. As shown in a slide above, we started with 650 unique issues (accounting for roughly 60,000 warnings in total), and after a lot of effort, we’re now in the final phase before we can finally enable this compiler option in mainline Linux. \ud83d\ude42<\/p>\n\n\n\n

I’ve talked about this work at multiple conferences. Below are a couple of presentations for those who want to learn more.<\/p>\n\n\n\n