Don't do pointer arithmetic on pointers to deallocated memory #106950
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Thanks! Would be good to add a regression test in fn miri_issue_2759() {
let mut input = "1".to_string();
input.replace_range(0..0, "0");
} |
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The Miri subtree was changed cc @rust-lang/miri |
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LGTM, but we should probably get a T-libs review. |
library/alloc/src/vec/splice.rs
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| // At this point draining is done and the only remaining tasks are splicing | ||
| // and moving things into the final place. | ||
| // Which means we can replace the slice::Iter with pointers that won't point to deallocated | ||
| // memory. This makes Miri happy. |
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It's not just about pleasing Miri, right?
| // memory. This makes Miri happy. | |
| // memory, and `Drain::drop` can still see that it's empty. This also makes Miri happy. |
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Well, logically it already was 0-length before, just the way it calculated the way was Miri-UB but not LLVM-UB because we're not emitting any hints that llvm could exploit. But that rephrase is not quite right either, it's about Drain being allowed to calculate the length at all.
vec::Splice can invalidate the slice::Iter inside vec::Drain. So we replace them with dangling pointers which, unlike ones to deallocated memory, are allowed.
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Don't do pointer arithmetic on pointers to deallocated memory vec::Splice can invalidate the slice::Iter inside vec::Drain. So we replace them with dangling pointers which, unlike ones to deallocated memory, are allowed. Fixes miri test failures. Fixes rust-lang/miri#2759
Rollup of 5 pull requests Successful merges: - rust-lang#103702 (Lift `T: Sized` bounds from some `strict_provenance` pointer methods) - rust-lang#106441 (relax reference requirement on SocketAddrExt::from_abstract_name) - rust-lang#106718 (finish trait solver skeleton work) - rust-lang#106950 (Don't do pointer arithmetic on pointers to deallocated memory) - rust-lang#107014 (rustdoc: remove deprecated / unused code from main.js) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
vec::Splice can invalidate the slice::Iter inside vec::Drain. So we replace them with dangling pointers which, unlike ones to deallocated memory, are allowed.
Fixes miri test failures.
Fixes rust-lang/miri#2759