Refactor runtime table management for more type-safety #8018
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This commit is an attempt to make the mistake fixed in bytecodealliance#8016 harder to happen again. This removes the `set_raw` helper entirely from tables and instead forces all callers to view the table as either a table of funcrefs or a table of externefs. By forcing that choice outwards instead of handling it inwards it enables dealing with a typed table in more contexts which should help naturally do the right thing.
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alexcrichton
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Feb 28, 2024
| let table = &mut *instance.get_defined_table(table); | ||
| table.init_func(funcref)?; |
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Relative to #8016 this was the other issue I found, this forgot to check whether the table was an externref table or funcref table and triggered a panic by assuming a global was a funcref.
fitzgen
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Feb 28, 2024
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This commit fixes an accidental issue introduced in bytecodealliance#8018 where using an element segment which had been dropped with an `externref` table would cause a panic. The panic happened due to an assertion that tables are being used with the right type of item and that was being mismatched. The underlying issue was that dropped element segments are modeled as an empty element segment but the empty element segment was using the "functions" encoding as opposed to the "expressions" encoding. This meant that code later assumed that due to the use of functions the table must be a table-of-functions, but this was not correct for externref-based tables. The fix in this commit is to instead model the encoding as an "expressions" list which means that the table type is dispatched on to call the appropriate initializer. There is no memory safety issue with this mistake as the assertion was specifically targetted at preventing memory safety. This does, however, enable any WebAssembly module to panic a host. Closes bytecodealliance#8281
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This commit fixes an accidental issue introduced in bytecodealliance#8018 where using an element segment which had been dropped with an `externref` table would cause a panic. The panic happened due to an assertion that tables are being used with the right type of item and that was being mismatched. The underlying issue was that dropped element segments are modeled as an empty element segment but the empty element segment was using the "functions" encoding as opposed to the "expressions" encoding. This meant that code later assumed that due to the use of functions the table must be a table-of-functions, but this was not correct for externref-based tables. The fix in this commit is to instead model the encoding as an "expressions" list which means that the table type is dispatched on to call the appropriate initializer. There is no memory safety issue with this mistake as the assertion was specifically targetted at preventing memory safety. This does, however, enable any WebAssembly module to panic a host. Closes bytecodealliance#8281
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This commit fixes an accidental issue introduced in bytecodealliance#8018 where using an element segment which had been dropped with an `externref` table would cause a panic. The panic happened due to an assertion that tables are being used with the right type of item and that was being mismatched. The underlying issue was that dropped element segments are modeled as an empty element segment but the empty element segment was using the "functions" encoding as opposed to the "expressions" encoding. This meant that code later assumed that due to the use of functions the table must be a table-of-functions, but this was not correct for externref-based tables. The fix in this commit is to instead model the encoding as an "expressions" list which means that the table type is dispatched on to call the appropriate initializer. There is no memory safety issue with this mistake as the assertion was specifically targetted at preventing memory safety. This does, however, enable any WebAssembly module to panic a host. Closes bytecodealliance#8281
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This commit fixes an accidental issue introduced in #8018 where using an element segment which had been dropped with an `externref` table would cause a panic. The panic happened due to an assertion that tables are being used with the right type of item and that was being mismatched. The underlying issue was that dropped element segments are modeled as an empty element segment but the empty element segment was using the "functions" encoding as opposed to the "expressions" encoding. This meant that code later assumed that due to the use of functions the table must be a table-of-functions, but this was not correct for externref-based tables. The fix in this commit is to instead model the encoding as an "expressions" list which means that the table type is dispatched on to call the appropriate initializer. There is no memory safety issue with this mistake as the assertion was specifically targetted at preventing memory safety. This does, however, enable any WebAssembly module to panic a host. Closes #8281
alexcrichton
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Apr 2, 2024
This commit fixes an accidental issue introduced in #8018 where using an element segment which had been dropped with an `externref` table would cause a panic. The panic happened due to an assertion that tables are being used with the right type of item and that was being mismatched. The underlying issue was that dropped element segments are modeled as an empty element segment but the empty element segment was using the "functions" encoding as opposed to the "expressions" encoding. This meant that code later assumed that due to the use of functions the table must be a table-of-functions, but this was not correct for externref-based tables. The fix in this commit is to instead model the encoding as an "expressions" list which means that the table type is dispatched on to call the appropriate initializer. There is no memory safety issue with this mistake as the assertion was specifically targetted at preventing memory safety. This does, however, enable any WebAssembly module to panic a host. Closes #8281
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This commit is an attempt to make the mistake fixed in #8016 harder to happen again. This removes the
set_rawhelper entirely from tables and instead forces all callers to view the table as either a table of funcrefs or a table of externefs. By forcing that choice outwards instead of handling it inwards it enables dealing with a typed table in more contexts which should help naturally do the right thing.