** Description changed: [Impact] Systems that use flash-kernel may end up installing the wrong kernel image. `linux-version sort` can provide different answers depending on how it is called (see Test Case). The stdin behavior appears to be a bug, and this is the mode flash-kernel uses. So, for example, a user with an arm64 u-boot system might end up booting 5.8.0-50-generic-64k instead of the expected 5.8.0-50-generic if both are installed. There maybe additional issues caused by this; for example, I found this with our automation that tests kernels on various arm64 platforms in version increasing order. Only after consulting logs did we realize that 64k kernels were not ever getting booted because the tooling (which uses argv mode) disagreed with the kernel installer (flash-kernel using stdin mode) about which kernel should be the default. + + It's possible this internal discrepancy can cause other issues due to + tools disagreeing about which kernel is the latest, but the flash-kernel + example is the only one I'm aware of at this point. [Test Case] Using argv: $ linux-version sort 5.8.0-50-generic 5.8.0-50-generic-64k 5.8.0-50-generic 5.8.0-50-generic-64k Using stdin (incorrect): $ cat versions.txt 5.8.0-50-generic 5.8.0-50-generic-64k $ cat versions.txt | linux-version sort 5.8.0-50-generic-64k 5.8.0-50-generic [Where Problems Could Occur] - An obvious place where problems could occur is if someone is relying on rebooting into the kernel that is incorrectly being sorted greatest. For those using only Ubuntu kernel packages, the only case I'm aware of is arm64 generic vs. generic-64k case used in the examples above. The generic-64k flavor is available in >= 20.10, as well as 20.04-hwe. ARM server users - those most likely to want the generic-64k flavor - are very unlikely to be using flash-kernel. The standard for ARM servers is UEFI firmware, which use GRUB and are unaffected by this change. We found this on an old HP m400 platform which is the only Ubuntu certified u-boot-based arm64 server, and is long out of support. + An obvious place where problems could occur is if someone is relying on rebooting into the kernel that is incorrectly being sorted greatest. For those using only Ubuntu kernel packages, the only case I'm aware of is arm64 generic vs. generic-64k case used in the examples above. The generic-64k flavor is available in >= 20.10, as well as 20.04-hwe. ARM server users - those most likely to want the generic-64k flavor - are very unlikely to be using flash-kernel. The standard for ARM servers is UEFI firmware, which use GRUB and are unaffected by this change. We found this on an HP m400 platform which is the only Ubuntu certified u-boot-based arm64 server.
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-base in Ubuntu. https://bugs.launchpad.net/bugs/1926985 Title: linux-version sort: argv and stdin behaviors differ Status in linux-base package in Ubuntu: Fix Released Status in linux-base source package in Bionic: In Progress Status in linux-base source package in Focal: In Progress Status in linux-base source package in Groovy: In Progress Status in linux-base source package in Hirsute: In Progress Status in linux-base source package in Impish: Fix Released Status in linux-base package in Debian: New Bug description: [Impact] Systems that use flash-kernel may end up installing the wrong kernel image. `linux-version sort` can provide different answers depending on how it is called (see Test Case). The stdin behavior appears to be a bug, and this is the mode flash-kernel uses. So, for example, a user with an arm64 u-boot system might end up booting 5.8.0-50-generic-64k instead of the expected 5.8.0-50-generic if both are installed. There maybe additional issues caused by this; for example, I found this with our automation that tests kernels on various arm64 platforms in version increasing order. Only after consulting logs did we realize that 64k kernels were not ever getting booted because the tooling (which uses argv mode) disagreed with the kernel installer (flash-kernel using stdin mode) about which kernel should be the default. It's possible this internal discrepancy can cause other issues due to tools disagreeing about which kernel is the latest, but the flash- kernel example is the only one I'm aware of at this point. [Test Case] Using argv: $ linux-version sort 5.8.0-50-generic 5.8.0-50-generic-64k 5.8.0-50-generic 5.8.0-50-generic-64k Using stdin (incorrect): $ cat versions.txt 5.8.0-50-generic 5.8.0-50-generic-64k $ cat versions.txt | linux-version sort 5.8.0-50-generic-64k 5.8.0-50-generic [Where Problems Could Occur] An obvious place where problems could occur is if someone is relying on rebooting into the kernel that is incorrectly being sorted greatest. For those using only Ubuntu kernel packages, the only case I'm aware of is arm64 generic vs. generic-64k case used in the examples above. The generic-64k flavor is available in >= 20.10, as well as 20.04-hwe. ARM server users - those most likely to want the generic-64k flavor - are very unlikely to be using flash-kernel. The standard for ARM servers is UEFI firmware, which use GRUB and are unaffected by this change. We found this on an HP m400 platform which is the only Ubuntu certified u-boot-based arm64 server. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-base/+bug/1926985/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
