https://lkml.org/lkml/2024/12/4/503 states that OABI support is quite obscure these days and will probably be outright unbuildable at some time in the future, but what you've found still qualifies as a (likely minor) security issue that should be properly reported as such. The kernel page on security reporting is https://docs.kernel.org/process/security-bugs.html
Hai there, kernel guys. Now... assuming you first rob a museum for a working ARM7TDMI-based board, then find a way to flash it with a kernel and a rootfs to boot it, and if your kernel has an obscure and not-used-anymore ABI enabled, and you then somehow give an untrusted party ability to run code on it, they could crash the kernel using this 8-byte userspace binary.
:)
It is academically cool, no more. Quite possibly some old industrial control stuff is still running on old ARM7 boards with OABI enabled, but (i hope) they are not exposed to third party code. I guess I could send in the one line patch, if i find the time. The fix is quite trivial, funnily enough. You simply mask off the bottom 2 bits instead of assuming that LR in ARM mode is 4-byte-aligned, since on ARM7 it might not be
