Remove the Paged memory initialization variant#4046
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alexcrichton merged 2 commits intoMay 5, 2022
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This commit simplifies the `MemoryInitialization` enum by removing the `Paged` variant. The `Paged` variant was originally added for uffd, but that support has now been removed in bytecodealliance#4040. This is no longer necessary but is still used as an intermediate step of becoming a `Static` variant of initialized memory (which copy-on-write uses). As a result this commit largely modifies the static initialization of memory steps and folds the two methods together.
peterhuene
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👍 just some comment typos.
Sorry for the delayed review, I missed this review request.
Co-authored-by: Peter Huene <peter@huene.dev>
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This commit fixes an issue introduced in bytecodealliance#4046 where the checks for ensuring that the memory initialization image for a module was constrained in its size failed to trigger and a very small module could produce an arbitrarily large memory image. The bug in question was that if a module only had empty data segments at arbitrarily small and large addresses then the loop which checks whether or not the image is allowed was skipped entirely since it was seen that the memory had no data size. The fix here is to skip segments that are empty to ensure that if the validation loop is skipped then no data segments will be processed to create the image (and the module won't end up having an image in the end).
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This commit fixes an issue introduced in #4046 where the checks for ensuring that the memory initialization image for a module was constrained in its size failed to trigger and a very small module could produce an arbitrarily large memory image. The bug in question was that if a module only had empty data segments at arbitrarily small and large addresses then the loop which checks whether or not the image is allowed was skipped entirely since it was seen that the memory had no data size. The fix here is to skip segments that are empty to ensure that if the validation loop is skipped then no data segments will be processed to create the image (and the module won't end up having an image in the end).
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…e#4112) This commit fixes an issue introduced in bytecodealliance#4046 where the checks for ensuring that the memory initialization image for a module was constrained in its size failed to trigger and a very small module could produce an arbitrarily large memory image. The bug in question was that if a module only had empty data segments at arbitrarily small and large addresses then the loop which checks whether or not the image is allowed was skipped entirely since it was seen that the memory had no data size. The fix here is to skip segments that are empty to ensure that if the validation loop is skipped then no data segments will be processed to create the image (and the module won't end up having an image in the end).
alexcrichton
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May 9, 2022
This commit fixes an issue introduced in #4046 where the checks for ensuring that the memory initialization image for a module was constrained in its size failed to trigger and a very small module could produce an arbitrarily large memory image. The bug in question was that if a module only had empty data segments at arbitrarily small and large addresses then the loop which checks whether or not the image is allowed was skipped entirely since it was seen that the memory had no data size. The fix here is to skip segments that are empty to ensure that if the validation loop is skipped then no data segments will be processed to create the image (and the module won't end up having an image in the end).
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This commit simplifies the
MemoryInitializationenum by removing thePagedvariant. ThePagedvariant was originally added for uffd, butthat support has now been removed in #4040. This is no longer necessary
but is still used as an intermediate step of becoming a
Staticvariantof initialized memory (which copy-on-write uses). As a result this
commit largely modifies the static initialization of memory steps and
folds the two methods together.