Rather than trust that the compiler will lay out the stack frame the
way we expect it to, use a union to force the correct alignment.
MFC after: 1 week
Fixes: 616f47f176c3 ("tunefs: Fix alignment warning on arm64")
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- rG FreeBSD src repository
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Buildable 71971 Build 68854: arc lint + arc unit
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You could also do something similar with the directory filling routine dir_clear_block() and the two functions that call it dir_insert() and dir_extend().
| sbin/tunefs/tunefs.c | ||
|---|---|---|
| 650–651 | Here we're adding a variable offset to the pointer before casting, we should assert that alignment is preserved but the union trick won't help us, and in fact a corrupt or manipulated file system can cause us to perform an unaligned read. | |
| 740–742 | Here we add a caller-provided offset to the pointer before casting, we should assert that alignment is preserved but the union trick won't help us. | |
| sbin/tunefs/tunefs.c | ||
|---|---|---|
| 650–651 | I mean, we know that it needs to be aligned at least enough for a struct direct given that it immediately uses offset 0 as such. That's why I suggested in the overall comment that __aligned would be useful if it works on stack vars to force over-alignment in these cases to just not worry about it. | |
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This commit seems to break the https://ci.freebsd.org/job/FreeBSD-main-amd64-test/28201/testReport/junit/sbin.tunefs/tunefs_test/suj/ test in CI. Locally reproducible with the following Bricoler (master-python branch) command:
$ bricoler freebsd-regression-test-suite --freebsd-src-git-checkout/url=/usr/src --freebsd-src-git-checkout/branch= --freebsd-src-build/kernel_config=GENERIC --freebsd-regression-test-suite/memory=3072 --freebsd-regression-test-suite/ncpus=2 --freebsd-regression-test-suite/parallelism=1 --freebsd-regression-test-suite/tests=sbin/tunefs/tunefs_test:suj