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fix some incorrect aliasing in the BTree #78476

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merged 1 commit into from
Nov 9, 2020
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This line is wrong:

ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);

When slice.as_mut_ptr() is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by slice.as_ptr(). (Miri currently misses this because raw pointers are not tracked properly.)

Cc @ssomers

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r? @sfackler

(rust_highfive has picked a reviewer for you, use r? to override)

@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Oct 28, 2020
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r? @Mark-Simulacrum

@jyn514 jyn514 added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Oct 28, 2020
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These functions are pretty fishy anyway (essentially shrinking or growing slices, which you can't really do), but this is a good fix nevertheless. @bors r+

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bors commented Nov 5, 2020

📌 Commit b0df3f7 has been approved by Mark-Simulacrum

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 5, 2020
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RalfJung commented Nov 5, 2020

Yeah, @ssomers has some further fixes. This is just the first thing that I found.

Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this pull request Nov 6, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc `@ssomers`
m-ou-se added a commit to m-ou-se/rust that referenced this pull request Nov 7, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ``@ssomers``
m-ou-se added a commit to m-ou-se/rust that referenced this pull request Nov 7, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ```@ssomers```
m-ou-se added a commit to m-ou-se/rust that referenced this pull request Nov 7, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ````@ssomers````
m-ou-se added a commit to m-ou-se/rust that referenced this pull request Nov 7, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc `````@ssomers`````
Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this pull request Nov 8, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ``````@ssomers``````
Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this pull request Nov 8, 2020
…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ```````@ssomers```````
bors added a commit to rust-lang-ci/rust that referenced this pull request Nov 9, 2020
Rollup of 12 pull requests

Successful merges:

 - rust-lang#77640 (Refactor IntErrorKind to avoid "underflow" terminology)
 - rust-lang#78026 (Define `fs::hard_link` to not follow symlinks.)
 - rust-lang#78114 (Recognize `private_intra_doc_links` as a lint)
 - rust-lang#78228 (Promote aarch64-unknown-linux-gnu to Tier 1)
 - rust-lang#78345 (Fix handling of item names for HIR)
 - rust-lang#78437 (BTreeMap: stop mistaking node for an orderly place)
 - rust-lang#78476 (fix some incorrect aliasing in the BTree)
 - rust-lang#78674 (inliner: Use substs_for_mir_body)
 - rust-lang#78748 (Implement destructuring assignment for tuples)
 - rust-lang#78868 (Fix tab focus on restyled switches)
 - rust-lang#78878 (Avoid overlapping cfg attributes when both macOS and aarch64)
 - rust-lang#78882 (Nicer hunk headers for rust files)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit 5639d97 into rust-lang:master Nov 9, 2020
@rustbot rustbot added this to the 1.49.0 milestone Nov 9, 2020
Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this pull request Nov 9, 2020
BTreeMap: fix pointer provenance rules

Fixes rust-lang#78477 and includes rust-lang#78476

r? `@Mark-Simulacrum`
@RalfJung RalfJung deleted the btree-alias branch November 12, 2020 14:02
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7 participants