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Undefined Behavior when T contains uninit bytes #3

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TyPR124 opened this issue Feb 7, 2020 · 2 comments · Fixed by #6
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Undefined Behavior when T contains uninit bytes #3

TyPR124 opened this issue Feb 7, 2020 · 2 comments · Fixed by #6

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@TyPR124
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TyPR124 commented Feb 7, 2020

Example: https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=d75fb532da27fbb22467a2b3b9439119

Use Tools -> Miri, it detects undefined behavior in Stowaway::new.
@TyPR124
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TyPR124 commented Feb 7, 2020

It appears that unconditionally using MaybeUninit::zeroed() in Stowaway::new() is enough to fix this.

https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=1a880674c2154bc3e70aef1bf4ae5d36

@TyPR124 TyPR124 mentioned this issue Feb 7, 2020
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@Lucretiel
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Ah, yes, I was a bit worried about this. I guess those bytes are allowed to be uninit even though they're still "read" whenever the structure is copied, because they're never "used".

@TyPR124 TyPR124 mentioned this issue Feb 10, 2020
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This was referenced Apr 8, 2020
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RustyYato added a commit to RustyYato/stowaway that referenced this issue Apr 8, 2020
@RustyYato
manually copy padding bytes when running miri
788ad00 
reorganize tests
remove faulty test from Lucretiel#3
RustyYato added a commit to RustyYato/stowaway that referenced this issue Apr 10, 2020
@RustyYato
add tests for uninit behavior as per Lucretiel#8
e5639ad 
removed bad tests from Lucretiel#3
@RustyYato RustyYato mentioned this issue Apr 10, 2020
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@Lucretiel @TyPR124