Ruby: Add post-update argument nodes for string constants

Author: hvitved

ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll

@@ -322,7 +322,11 @@ private class Argument extends CfgNodes::ExprCfgNode {
 
 /** Holds if `n` is not a constant expression. */
 predicate isNonConstantExpr(CfgNodes::ExprCfgNode n) {
-  not exists(n.getConstantValue()) and
+  not exists(ConstantValue cv |
+    cv = n.getConstantValue() and
+    // strings are mutable in Ruby
+    not cv.isString(_)
+  ) and
   not n.getExpr() instanceof ConstantAccess
 }
 

ruby/ql/test/library-tests/dataflow/global/instance_variables.rb

@@ -70,7 +70,7 @@ def initialize x
 foo3.set_field(taint(22))
 sink(foo3.field) # $ hasValueFlow=22
 
-foo4 = "hello"
+foo4 = 4
 foo4.other = taint(23)
 sink(foo4.other) # no field flow for constants
 

ruby/ql/test/library-tests/dataflow/local/DataflowStep.expected

@@ -2676,6 +2676,7 @@
 | local_dataflow.rb:131:7:131:8 | "" | local_dataflow.rb:131:3:131:8 | ... = ... |
 | local_dataflow.rb:132:6:132:11 | [post] self | local_dataflow.rb:133:8:133:13 | self |
 | local_dataflow.rb:132:6:132:11 | self | local_dataflow.rb:133:8:133:13 | self |
+| local_dataflow.rb:132:10:132:10 | [post] x | local_dataflow.rb:133:12:133:12 | x |
 | local_dataflow.rb:132:10:132:10 | x | local_dataflow.rb:133:12:133:12 | x |
 | local_dataflow.rb:132:12:148:10 | then ... | local_dataflow.rb:132:3:149:5 | if ... |
 | local_dataflow.rb:133:5:139:7 | SSA phi read(self) | local_dataflow.rb:141:9:141:14 | self |
@@ -2686,17 +2687,20 @@
 | local_dataflow.rb:133:8:133:13 | self | local_dataflow.rb:133:18:133:23 | self |
 | local_dataflow.rb:133:8:133:23 | SSA phi read(self) | local_dataflow.rb:134:7:134:12 | self |
 | local_dataflow.rb:133:8:133:23 | SSA phi read(x) | local_dataflow.rb:134:11:134:11 | x |
+| local_dataflow.rb:133:12:133:12 | [post] x | local_dataflow.rb:133:22:133:22 | x |
 | local_dataflow.rb:133:12:133:12 | x | local_dataflow.rb:133:22:133:22 | x |
 | local_dataflow.rb:133:18:133:23 | [post] self | local_dataflow.rb:136:7:136:12 | self |
 | local_dataflow.rb:133:18:133:23 | call to use | local_dataflow.rb:133:8:133:23 | [false] ... \|\| ... |
 | local_dataflow.rb:133:18:133:23 | call to use | local_dataflow.rb:133:8:133:23 | [true] ... \|\| ... |
 | local_dataflow.rb:133:18:133:23 | self | local_dataflow.rb:136:7:136:12 | self |
+| local_dataflow.rb:133:22:133:22 | [post] x | local_dataflow.rb:136:11:136:11 | x |
 | local_dataflow.rb:133:22:133:22 | x | local_dataflow.rb:136:11:136:11 | x |
 | local_dataflow.rb:133:24:134:12 | then ... | local_dataflow.rb:133:5:139:7 | if ... |
 | local_dataflow.rb:134:7:134:12 | call to use | local_dataflow.rb:133:24:134:12 | then ... |
 | local_dataflow.rb:135:5:138:9 | else ... | local_dataflow.rb:133:5:139:7 | if ... |
 | local_dataflow.rb:136:7:136:12 | [post] self | local_dataflow.rb:137:10:137:15 | self |
 | local_dataflow.rb:136:7:136:12 | self | local_dataflow.rb:137:10:137:15 | self |
+| local_dataflow.rb:136:11:136:11 | [post] x | local_dataflow.rb:137:14:137:14 | x |
 | local_dataflow.rb:136:11:136:11 | x | local_dataflow.rb:137:14:137:14 | x |
 | local_dataflow.rb:137:7:138:9 | SSA phi read(self) | local_dataflow.rb:133:5:139:7 | SSA phi read(self) |
 | local_dataflow.rb:137:7:138:9 | SSA phi read(x) | local_dataflow.rb:133:5:139:7 | SSA phi read(x) |
@@ -2705,6 +2709,7 @@
 | local_dataflow.rb:137:10:137:15 | self | local_dataflow.rb:137:21:137:26 | self |
 | local_dataflow.rb:137:10:137:26 | SSA phi read(self) | local_dataflow.rb:137:7:138:9 | SSA phi read(self) |
 | local_dataflow.rb:137:10:137:26 | SSA phi read(x) | local_dataflow.rb:137:7:138:9 | SSA phi read(x) |
+| local_dataflow.rb:137:14:137:14 | [post] x | local_dataflow.rb:137:25:137:25 | x |
 | local_dataflow.rb:137:14:137:14 | x | local_dataflow.rb:137:25:137:25 | x |
 | local_dataflow.rb:137:20:137:26 | [false] ! ... | local_dataflow.rb:137:10:137:26 | [false] ... && ... |
 | local_dataflow.rb:137:20:137:26 | [true] ! ... | local_dataflow.rb:137:10:137:26 | [true] ... && ... |
@@ -2717,6 +2722,7 @@
 | local_dataflow.rb:141:8:141:37 | SSA phi read(x) | local_dataflow.rb:141:5:145:7 | SSA phi read(x) |
 | local_dataflow.rb:141:9:141:14 | [post] self | local_dataflow.rb:141:20:141:25 | self |
 | local_dataflow.rb:141:9:141:14 | self | local_dataflow.rb:141:20:141:25 | self |
+| local_dataflow.rb:141:13:141:13 | [post] x | local_dataflow.rb:141:24:141:24 | x |
 | local_dataflow.rb:141:13:141:13 | x | local_dataflow.rb:141:24:141:24 | x |
 | local_dataflow.rb:141:19:141:37 | [false] ( ... ) | local_dataflow.rb:141:8:141:37 | [false] ... \|\| ... |
 | local_dataflow.rb:141:19:141:37 | [true] ( ... ) | local_dataflow.rb:141:8:141:37 | [true] ... \|\| ... |
@@ -2726,6 +2732,7 @@
 | local_dataflow.rb:141:20:141:36 | SSA phi read(x) | local_dataflow.rb:143:15:143:15 | x |
 | local_dataflow.rb:141:20:141:36 | [false] ... && ... | local_dataflow.rb:141:19:141:37 | [false] ( ... ) |
 | local_dataflow.rb:141:20:141:36 | [true] ... && ... | local_dataflow.rb:141:19:141:37 | [true] ( ... ) |
+| local_dataflow.rb:141:24:141:24 | [post] x | local_dataflow.rb:141:35:141:35 | x |
 | local_dataflow.rb:141:24:141:24 | x | local_dataflow.rb:141:35:141:35 | x |
 | local_dataflow.rb:141:30:141:36 | [false] ! ... | local_dataflow.rb:141:20:141:36 | [false] ... && ... |
 | local_dataflow.rb:141:30:141:36 | [true] ! ... | local_dataflow.rb:141:20:141:36 | [true] ... && ... |
@@ -2740,12 +2747,14 @@
 | local_dataflow.rb:143:11:143:16 | self | local_dataflow.rb:143:21:143:26 | self |
 | local_dataflow.rb:143:11:143:26 | SSA phi read(self) | local_dataflow.rb:144:11:144:16 | self |
 | local_dataflow.rb:143:11:143:26 | SSA phi read(x) | local_dataflow.rb:144:15:144:15 | x |
+| local_dataflow.rb:143:15:143:15 | [post] x | local_dataflow.rb:143:25:143:25 | x |
 | local_dataflow.rb:143:15:143:15 | x | local_dataflow.rb:143:25:143:25 | x |
 | local_dataflow.rb:143:21:143:26 | call to use | local_dataflow.rb:143:11:143:26 | [false] ... \|\| ... |
 | local_dataflow.rb:143:21:143:26 | call to use | local_dataflow.rb:143:11:143:26 | [true] ... \|\| ... |
 | local_dataflow.rb:143:27:144:16 | then ... | local_dataflow.rb:143:5:144:16 | elsif ... |
 | local_dataflow.rb:144:11:144:16 | call to use | local_dataflow.rb:143:27:144:16 | then ... |
 | local_dataflow.rb:147:5:147:10 | [post] self | local_dataflow.rb:148:5:148:10 | self |
 | local_dataflow.rb:147:5:147:10 | self | local_dataflow.rb:148:5:148:10 | self |
+| local_dataflow.rb:147:9:147:9 | [post] x | local_dataflow.rb:148:9:148:9 | x |
 | local_dataflow.rb:147:9:147:9 | x | local_dataflow.rb:148:9:148:9 | x |
 | local_dataflow.rb:148:5:148:10 | call to use | local_dataflow.rb:132:12:148:10 | then ... |

ruby/ql/test/library-tests/dataflow/local/TaintStep.expected

@@ -3167,6 +3167,7 @@
 | local_dataflow.rb:131:7:131:8 | "" | local_dataflow.rb:131:3:131:8 | ... = ... |
 | local_dataflow.rb:132:6:132:11 | [post] self | local_dataflow.rb:133:8:133:13 | self |
 | local_dataflow.rb:132:6:132:11 | self | local_dataflow.rb:133:8:133:13 | self |
+| local_dataflow.rb:132:10:132:10 | [post] x | local_dataflow.rb:133:12:133:12 | x |
 | local_dataflow.rb:132:10:132:10 | x | local_dataflow.rb:133:12:133:12 | x |
 | local_dataflow.rb:132:12:148:10 | then ... | local_dataflow.rb:132:3:149:5 | if ... |
 | local_dataflow.rb:133:5:139:7 | SSA phi read(self) | local_dataflow.rb:141:9:141:14 | self |
@@ -3177,17 +3178,20 @@
 | local_dataflow.rb:133:8:133:13 | self | local_dataflow.rb:133:18:133:23 | self |
 | local_dataflow.rb:133:8:133:23 | SSA phi read(self) | local_dataflow.rb:134:7:134:12 | self |
 | local_dataflow.rb:133:8:133:23 | SSA phi read(x) | local_dataflow.rb:134:11:134:11 | x |
+| local_dataflow.rb:133:12:133:12 | [post] x | local_dataflow.rb:133:22:133:22 | x |
 | local_dataflow.rb:133:12:133:12 | x | local_dataflow.rb:133:22:133:22 | x |
 | local_dataflow.rb:133:18:133:23 | [post] self | local_dataflow.rb:136:7:136:12 | self |
 | local_dataflow.rb:133:18:133:23 | call to use | local_dataflow.rb:133:8:133:23 | [false] ... \|\| ... |
 | local_dataflow.rb:133:18:133:23 | call to use | local_dataflow.rb:133:8:133:23 | [true] ... \|\| ... |
 | local_dataflow.rb:133:18:133:23 | self | local_dataflow.rb:136:7:136:12 | self |
+| local_dataflow.rb:133:22:133:22 | [post] x | local_dataflow.rb:136:11:136:11 | x |
 | local_dataflow.rb:133:22:133:22 | x | local_dataflow.rb:136:11:136:11 | x |
 | local_dataflow.rb:133:24:134:12 | then ... | local_dataflow.rb:133:5:139:7 | if ... |
 | local_dataflow.rb:134:7:134:12 | call to use | local_dataflow.rb:133:24:134:12 | then ... |
 | local_dataflow.rb:135:5:138:9 | else ... | local_dataflow.rb:133:5:139:7 | if ... |
 | local_dataflow.rb:136:7:136:12 | [post] self | local_dataflow.rb:137:10:137:15 | self |
 | local_dataflow.rb:136:7:136:12 | self | local_dataflow.rb:137:10:137:15 | self |
+| local_dataflow.rb:136:11:136:11 | [post] x | local_dataflow.rb:137:14:137:14 | x |
 | local_dataflow.rb:136:11:136:11 | x | local_dataflow.rb:137:14:137:14 | x |
 | local_dataflow.rb:137:7:138:9 | SSA phi read(self) | local_dataflow.rb:133:5:139:7 | SSA phi read(self) |
 | local_dataflow.rb:137:7:138:9 | SSA phi read(x) | local_dataflow.rb:133:5:139:7 | SSA phi read(x) |
@@ -3196,6 +3200,7 @@
 | local_dataflow.rb:137:10:137:15 | self | local_dataflow.rb:137:21:137:26 | self |
 | local_dataflow.rb:137:10:137:26 | SSA phi read(self) | local_dataflow.rb:137:7:138:9 | SSA phi read(self) |
 | local_dataflow.rb:137:10:137:26 | SSA phi read(x) | local_dataflow.rb:137:7:138:9 | SSA phi read(x) |
+| local_dataflow.rb:137:14:137:14 | [post] x | local_dataflow.rb:137:25:137:25 | x |
 | local_dataflow.rb:137:14:137:14 | x | local_dataflow.rb:137:25:137:25 | x |
 | local_dataflow.rb:137:20:137:26 | [false] ! ... | local_dataflow.rb:137:10:137:26 | [false] ... && ... |
 | local_dataflow.rb:137:20:137:26 | [true] ! ... | local_dataflow.rb:137:10:137:26 | [true] ... && ... |
@@ -3212,6 +3217,7 @@
 | local_dataflow.rb:141:9:141:14 | call to use | local_dataflow.rb:141:8:141:14 | [false] ! ... |
 | local_dataflow.rb:141:9:141:14 | call to use | local_dataflow.rb:141:8:141:14 | [true] ! ... |
 | local_dataflow.rb:141:9:141:14 | self | local_dataflow.rb:141:20:141:25 | self |
+| local_dataflow.rb:141:13:141:13 | [post] x | local_dataflow.rb:141:24:141:24 | x |
 | local_dataflow.rb:141:13:141:13 | x | local_dataflow.rb:141:24:141:24 | x |
 | local_dataflow.rb:141:19:141:37 | [false] ( ... ) | local_dataflow.rb:141:8:141:37 | [false] ... \|\| ... |
 | local_dataflow.rb:141:19:141:37 | [true] ( ... ) | local_dataflow.rb:141:8:141:37 | [true] ... \|\| ... |
@@ -3221,6 +3227,7 @@
 | local_dataflow.rb:141:20:141:36 | SSA phi read(x) | local_dataflow.rb:143:15:143:15 | x |
 | local_dataflow.rb:141:20:141:36 | [false] ... && ... | local_dataflow.rb:141:19:141:37 | [false] ( ... ) |
 | local_dataflow.rb:141:20:141:36 | [true] ... && ... | local_dataflow.rb:141:19:141:37 | [true] ( ... ) |
+| local_dataflow.rb:141:24:141:24 | [post] x | local_dataflow.rb:141:35:141:35 | x |
 | local_dataflow.rb:141:24:141:24 | x | local_dataflow.rb:141:35:141:35 | x |
 | local_dataflow.rb:141:30:141:36 | [false] ! ... | local_dataflow.rb:141:20:141:36 | [false] ... && ... |
 | local_dataflow.rb:141:30:141:36 | [true] ! ... | local_dataflow.rb:141:20:141:36 | [true] ... && ... |
@@ -3237,12 +3244,14 @@
 | local_dataflow.rb:143:11:143:16 | self | local_dataflow.rb:143:21:143:26 | self |
 | local_dataflow.rb:143:11:143:26 | SSA phi read(self) | local_dataflow.rb:144:11:144:16 | self |
 | local_dataflow.rb:143:11:143:26 | SSA phi read(x) | local_dataflow.rb:144:15:144:15 | x |
+| local_dataflow.rb:143:15:143:15 | [post] x | local_dataflow.rb:143:25:143:25 | x |
 | local_dataflow.rb:143:15:143:15 | x | local_dataflow.rb:143:25:143:25 | x |
 | local_dataflow.rb:143:21:143:26 | call to use | local_dataflow.rb:143:11:143:26 | [false] ... \|\| ... |
 | local_dataflow.rb:143:21:143:26 | call to use | local_dataflow.rb:143:11:143:26 | [true] ... \|\| ... |
 | local_dataflow.rb:143:27:144:16 | then ... | local_dataflow.rb:143:5:144:16 | elsif ... |
 | local_dataflow.rb:144:11:144:16 | call to use | local_dataflow.rb:143:27:144:16 | then ... |
 | local_dataflow.rb:147:5:147:10 | [post] self | local_dataflow.rb:148:5:148:10 | self |
 | local_dataflow.rb:147:5:147:10 | self | local_dataflow.rb:148:5:148:10 | self |
+| local_dataflow.rb:147:9:147:9 | [post] x | local_dataflow.rb:148:9:148:9 | x |
 | local_dataflow.rb:147:9:147:9 | x | local_dataflow.rb:148:9:148:9 | x |
 | local_dataflow.rb:148:5:148:10 | call to use | local_dataflow.rb:132:12:148:10 | then ... |

ruby/ql/test/library-tests/frameworks/action_controller/params-flow.expected

@@ -116,6 +116,9 @@ edges
 | params_flow.rb:198:5:198:10 | call to params | params_flow.rb:198:5:198:17 | ...[...] | provenance |  |
 | params_flow.rb:198:5:198:17 | ...[...] | params_flow.rb:198:28:198:28 | [post] a | provenance |  |
 | params_flow.rb:198:28:198:28 | [post] a | params_flow.rb:199:10:199:10 | a | provenance |  |
+| params_flow.rb:204:5:204:10 | call to params | params_flow.rb:204:5:204:17 | ...[...] | provenance |  |
+| params_flow.rb:204:5:204:17 | ...[...] | params_flow.rb:204:28:204:28 | [post] a | provenance |  |
+| params_flow.rb:204:28:204:28 | [post] a | params_flow.rb:205:10:205:10 | a | provenance |  |
 nodes
 | filter_flow.rb:14:5:14:8 | [post] self [@foo] | semmle.label | [post] self [@foo] |
 | filter_flow.rb:14:12:14:17 | call to params | semmle.label | call to params |
@@ -279,6 +282,10 @@ nodes
 | params_flow.rb:198:5:198:17 | ...[...] | semmle.label | ...[...] |
 | params_flow.rb:198:28:198:28 | [post] a | semmle.label | [post] a |
 | params_flow.rb:199:10:199:10 | a | semmle.label | a |
+| params_flow.rb:204:5:204:10 | call to params | semmle.label | call to params |
+| params_flow.rb:204:5:204:17 | ...[...] | semmle.label | ...[...] |
+| params_flow.rb:204:28:204:28 | [post] a | semmle.label | [post] a |
+| params_flow.rb:205:10:205:10 | a | semmle.label | a |
 subpaths
 #select
 | filter_flow.rb:21:10:21:13 | @foo | filter_flow.rb:14:12:14:17 | call to params | filter_flow.rb:21:10:21:13 | @foo | $@ | filter_flow.rb:14:12:14:17 | call to params | call to params |
@@ -338,3 +345,4 @@ subpaths
 | params_flow.rb:190:10:190:44 | call to headers | params_flow.rb:190:10:190:15 | call to params | params_flow.rb:190:10:190:44 | call to headers | $@ | params_flow.rb:190:10:190:15 | call to params | call to params |
 | params_flow.rb:194:10:194:47 | call to read | params_flow.rb:194:10:194:15 | call to params | params_flow.rb:194:10:194:47 | call to read | $@ | params_flow.rb:194:10:194:15 | call to params | call to params |
 | params_flow.rb:199:10:199:10 | a | params_flow.rb:198:5:198:10 | call to params | params_flow.rb:199:10:199:10 | a | $@ | params_flow.rb:198:5:198:10 | call to params | call to params |
+| params_flow.rb:205:10:205:10 | a | params_flow.rb:204:5:204:10 | call to params | params_flow.rb:205:10:205:10 | a | $@ | params_flow.rb:204:5:204:10 | call to params | call to params |

ruby/ql/test/library-tests/frameworks/action_controller/params_flow.rb

@@ -202,6 +202,6 @@ def m40(a)
   def m41
     a = ""
     params[:file].read(nil,a)
-    sink a # $ MISSING:hasTaintFlow
+    sink a # $ hasTaintFlow
   end
 end