Skip to content

C#: Add support for flow through side-effects on static fields #16576

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
hvitved merged 2 commits into from
Aug 13, 2024
Merged

C#: Add support for flow through side-effects on static fields #16576

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
29c204b
C#: Add a data flow test for side effects on static fields
hvitved May 23, 2024
1bcac50
C#: Add support for flow through side-effects on static fields
hvitved May 23, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions csharp/ql/lib/change-notes/2024-05-23-static-field-side-effect.md
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
---
category: majorAnalysis
---
* Added support for data flow through side-effects on static fields. For example, when a static field containing an array is updated.
6 changes: 4 additions & 2 deletions csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2095,9 +2095,11 @@ predicate jumpStep(Node pred, Node succ) {
f.getAnAssignedValue() = pred.asExpr() and
succ = TFlowInsensitiveFieldNode(f)
or
exists(FieldOrPropertyRead fr |
exists(FieldOrPropertyRead fr | f.getAnAccess() = fr |
fr = pred.(PostUpdateNode).getPreUpdateNode().asExpr() and
succ = TFlowInsensitiveFieldNode(f)
or
pred = TFlowInsensitiveFieldNode(f) and
f.getAnAccess() = fr and
fr = succ.asExpr() and
fr.hasNonlocalValue()
)
Expand Down
24 changes: 24 additions & 0 deletions csharp/ql/test/library-tests/dataflow/fields/FieldFlow.expected
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1152,6 +1152,16 @@ edges
| J.cs:125:14:125:14 | access to local variable a : Int32[] [element] : Int32 | J.cs:125:14:125:17 | access to array element : Int32 | provenance | |
| J.cs:125:14:125:17 | access to array element : Int32 | J.cs:125:14:125:17 | (...) ... | provenance | |
| J.cs:125:14:125:17 | access to array element : Int32 | J.cs:125:14:125:17 | (...) ... | provenance | |
| K.cs:7:13:7:13 | access to local variable o : String | K.cs:8:22:8:22 | access to local variable o : String | provenance | |
| K.cs:7:13:7:13 | access to local variable o : String | K.cs:8:22:8:22 | access to local variable o : String | provenance | |
| K.cs:7:17:7:33 | call to method Source<String> : String | K.cs:7:13:7:13 | access to local variable o : String | provenance | |
| K.cs:7:17:7:33 | call to method Source<String> : String | K.cs:7:13:7:13 | access to local variable o : String | provenance | |
| K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | provenance | |
| K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | provenance | |
| K.cs:8:22:8:22 | access to local variable o : String | K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | provenance | |
| K.cs:8:22:8:22 | access to local variable o : String | K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | provenance | |
| K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | K.cs:13:14:13:23 | access to array element | provenance | |
| K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | K.cs:13:14:13:23 | access to array element | provenance | |
nodes
| A.cs:5:13:5:13 | access to local variable c : C | semmle.label | access to local variable c : C |
| A.cs:5:13:5:13 | access to local variable c : C | semmle.label | access to local variable c : C |
Expand Down Expand Up @@ -2393,6 +2403,18 @@ nodes
| J.cs:125:14:125:17 | (...) ... | semmle.label | (...) ... |
| J.cs:125:14:125:17 | access to array element : Int32 | semmle.label | access to array element : Int32 |
| J.cs:125:14:125:17 | access to array element : Int32 | semmle.label | access to array element : Int32 |
| K.cs:7:13:7:13 | access to local variable o : String | semmle.label | access to local variable o : String |
| K.cs:7:13:7:13 | access to local variable o : String | semmle.label | access to local variable o : String |
| K.cs:7:17:7:33 | call to method Source<String> : String | semmle.label | call to method Source<String> : String |
| K.cs:7:17:7:33 | call to method Source<String> : String | semmle.label | call to method Source<String> : String |
| K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | semmle.label | [post] access to field Strings : String[] [element] : String |
| K.cs:8:9:8:15 | [post] access to field Strings : String[] [element] : String | semmle.label | [post] access to field Strings : String[] [element] : String |
| K.cs:8:22:8:22 | access to local variable o : String | semmle.label | access to local variable o : String |
| K.cs:8:22:8:22 | access to local variable o : String | semmle.label | access to local variable o : String |
| K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | semmle.label | access to field Strings : String[] [element] : String |
| K.cs:13:14:13:20 | access to field Strings : String[] [element] : String | semmle.label | access to field Strings : String[] [element] : String |
| K.cs:13:14:13:23 | access to array element | semmle.label | access to array element |
| K.cs:13:14:13:23 | access to array element | semmle.label | access to array element |
subpaths
| A.cs:6:24:6:24 | access to local variable c : C | A.cs:147:32:147:32 | c : C | A.cs:149:20:149:27 | object creation of type B : B [field c] : C | A.cs:6:17:6:25 | call to method Make : B [field c] : C |
| A.cs:6:24:6:24 | access to local variable c : C | A.cs:147:32:147:32 | c : C | A.cs:149:20:149:27 | object creation of type B : B [field c] : C | A.cs:6:17:6:25 | call to method Make : B [field c] : C |
Expand Down Expand Up @@ -2647,3 +2669,5 @@ subpaths
| J.cs:107:14:107:17 | access to property Y | J.cs:105:32:105:48 | call to method Source<Object> : Object | J.cs:107:14:107:17 | access to property Y | $@ | J.cs:105:32:105:48 | call to method Source<Object> : Object | call to method Source<Object> : Object |
| J.cs:125:14:125:17 | (...) ... | J.cs:119:20:119:34 | call to method Source<Int32> : Int32 | J.cs:125:14:125:17 | (...) ... | $@ | J.cs:119:20:119:34 | call to method Source<Int32> : Int32 | call to method Source<Int32> : Int32 |
| J.cs:125:14:125:17 | (...) ... | J.cs:119:20:119:34 | call to method Source<Int32> : Int32 | J.cs:125:14:125:17 | (...) ... | $@ | J.cs:119:20:119:34 | call to method Source<Int32> : Int32 | call to method Source<Int32> : Int32 |
| K.cs:13:14:13:23 | access to array element | K.cs:7:17:7:33 | call to method Source<String> : String | K.cs:13:14:13:23 | access to array element | $@ | K.cs:7:17:7:33 | call to method Source<String> : String | call to method Source<String> : String |
| K.cs:13:14:13:23 | access to array element | K.cs:7:17:7:33 | call to method Source<String> : String | K.cs:13:14:13:23 | access to array element | $@ | K.cs:7:17:7:33 | call to method Source<String> : String | call to method Source<String> : String |
19 changes: 19 additions & 0 deletions csharp/ql/test/library-tests/dataflow/fields/K.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
public class K
{
static string[] Strings = new string[10];

private void M1()
{
var o = Source<string>(1);
Strings[0] = o;
}

private void M2()
{
Sink(Strings[0]); // $ hasValueFlow=1
}

public static void Sink(object o) { }

static T Source<T>(object source) => throw null;
}