Create rule S7433 Raw pointers should not be casted to slices with differently sized elements (#4774)

* Create rule S7433

* Update metadata.json

* Update rule.adoc

* Update rule.adoc

* Update metadata.json

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Co-authored-by: sallaigy <sallaigy@users.noreply.github.com>
Co-authored-by: Gyula Sallai <gyula.sallai@sonarsource.com>
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}

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{
"title": "Raw pointers should not be casted to slices with differently sized elements",
"type": "BUG",
"status": "ready",
"remediation": {
"func": "Constant\/Issue",
"constantCost": "5min"
},
"tags": [
"clippy"
],
"defaultSeverity": "Blocker",
"ruleSpecification": "RSPEC-7433",
"sqKey": "S7433",
"scope": "All",
"defaultQualityProfiles": ["Sonar way"],
"quickfix": "unknown",
"code": {
"impacts": {
"RELIABILITY": "HIGH"
},
"attribute": "LOGICAL"
}
}

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== Why is this an issue?
When casting a raw pointer to a slice, the produced raw pointer does not correctly update its length metadata, leading to potential issues such as creating a slice with less data than intended or more data, risking undefined behavior upon dereferencing.
== How to fix it
Use `ptr::slice_from_raw_parts` to construct a slice from a data pointer and the correct length.
=== Code examples
==== Noncompliant code example
[source,rust,diff-id=1,diff-type=noncompliant]
----
let a = [1_u8, 2, 3, 4];
let p = &a as *const [u8] as *const [u32];
unsafe {
println!("{:?}", &*p); // Noncompliant: Undefined behavior
}
----
==== Compliant solution
[source,rust,diff-id=1,diff-type=compliant]
----
let a = [1_i32, 2, 3, 4];
let old_ptr = &a as *const [i32];
// The data pointer is cast to a pointer to the target `u8` not `[u8]`
// The length comes from the known length of 4 i32s times the 4 bytes per i32
let new_ptr = core::ptr::slice_from_raw_parts(old_ptr as *const u8, 16);
unsafe {
println!("{:?}", &*new_ptr);
}
----
== Resources
=== Documentation
* Clippy Lints - https://rust-lang.github.io/rust-clippy/master/index.html#cast_slice_different_sizes