Fix misaligned stack access for map keys #2012
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viktormalik
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Looks good but maybe is it good to align to 1 only if the buffer size is not multiple of eight to prevent slow down? |
Hm, we could do this, but the code would get a bit more complicated (we'd have to track the current alignment while creating the key). Not sure if it's worth it. |
viktormalik
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In the end the code is not much more complex and since the key will be mostly aligned, it makes sense to align to 1 only if necessary. |
mmisono
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fbs
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Construction of multi-value map keys on the stack is done in multiple places, so it is more practical to have a separate function for it.
Using multi-value keys with one component not aligned to 8 bytes (e.g. by using buf) may cause misaligned stack access errors. If a component is not aligned, we set the alignmnent of all the following components to 1. Appropriate runtime tests are added.
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Using multi-value keys with one component not aligned to 8 bytes (e.g. by using
buf) may cause misaligned stack access errors. This is because scalar components of keys (e.g. those ofinttype) are stored onto stack with 8-byte alignment.The simplest fix is to change the alignment to 1. Hopefully, this shouldn't cause any trouble since we read the keys byte-by-byte anyways.
Fixes #2006.
Checklist
man/adoc/bpftrace.adocand if needed indocs/reference_guide.mdCHANGELOG.md