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Merge pull request #13191 from MathiasVP/fix-pointer-pointee-conflation

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C++: Fix pointer/pointee conflation
This commit is contained in:
Mathias Vorreiter Pedersen
2023-05-18 13:09:10 +01:00
committed by GitHub
parent 2e734755fb 402212bab9
commit 8cf25ba421
7 changed files with 33 additions and 45 deletions
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33
cpp/ql/lib/semmle/code/cpp/ir/dataflow/internal/SsaInternals.qll
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@@ -657,24 +657,16 @@ private predicate indirectConversionFlowStep(Node nFrom, Node nTo) {
* So this predicate recurses back along conversions and `PointerArithmeticInstruction`s to find the
* first use that has provides use-use flow, and uses that target as the target of the `nodeFrom`.
*/
private predicate adjustForPointerArith(
DefOrUse defOrUse, Node nodeFrom, UseOrPhi use, boolean uncertain
) {
nodeFrom = any(PostUpdateNode pun).getPreUpdateNode() and
exists(Node adjusted |
indirectConversionFlowStep*(adjusted, nodeFrom) and
nodeToDefOrUse(adjusted, defOrUse, uncertain) and
private predicate adjustForPointerArith(PostUpdateNode pun, UseOrPhi use) {
exists(DefOrUse defOrUse, Node adjusted |
indirectConversionFlowStep*(adjusted, pun.getPreUpdateNode()) and
nodeToDefOrUse(adjusted, defOrUse, _) and
adjacentDefRead(defOrUse, use)
)
}
private predicate ssaFlowImpl(SsaDefOrUse defOrUse, Node nodeFrom, Node nodeTo, boolean uncertain) {
// `nodeFrom = any(PostUpdateNode pun).getPreUpdateNode()` is implied by adjustedForPointerArith.
exists(UseOrPhi use |
adjustForPointerArith(defOrUse, nodeFrom, use, uncertain) and
useToNode(use, nodeTo)
or
not nodeFrom = any(PostUpdateNode pun).getPreUpdateNode() and
nodeToDefOrUse(nodeFrom, defOrUse, uncertain) and
adjacentDefRead(defOrUse, use) and
useToNode(use, nodeTo) and
@@ -719,14 +711,19 @@ predicate ssaFlow(Node nodeFrom, Node nodeTo) {
)
}
private predicate isArgumentOfCallable(DataFlowCall call, ArgumentNode arg) {
arg.argumentOf(call, _)
}
/** Holds if there is def-use or use-use flow from `pun` to `nodeTo`. */
predicate postUpdateFlow(PostUpdateNode pun, Node nodeTo) {
exists(Node preUpdate, Node nFrom, boolean uncertain, SsaDefOrUse defOrUse |
exists(UseOrPhi use, Node preUpdate |
adjustForPointerArith(pun, use) and
useToNode(use, nodeTo) and
preUpdate = pun.getPreUpdateNode() and
ssaFlowImpl(defOrUse, nFrom, nodeTo, uncertain)
|
if uncertain = true
then preUpdate = [nFrom, getAPriorDefinition(defOrUse)]
else preUpdate = nFrom
not exists(DataFlowCall call |
isArgumentOfCallable(call, preUpdate) and isArgumentOfCallable(call, nodeTo)
)
)
}

8
cpp/ql/test/library-tests/dataflow/dataflow-tests/clang.cpp
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@@ -1,7 +1,7 @@
// semmle-extractor-options: --edg --clang
int source();
void sink(int); void sink(const int *); void sink(int **);
void sink(int); void sink(const int *); void sink(int **); void indirect_sink(...);
struct twoIntFields {
int m1, m2;
@@ -19,7 +19,8 @@ void following_pointers( // $ ast-def=sourceStruct1_ptr
sink(sourceArray1[0]); // no flow
sink(*sourceArray1); // no flow
sink(&sourceArray1); // $ ast,ir // [should probably be taint only]
sink(&sourceArray1); // $ ast // [should probably be taint only]
indirect_sink(&sourceArray1); // $ ast,ir
sink(sourceStruct1.m1); // no flow
sink(sourceStruct1_ptr->m1); // no flow
@@ -48,5 +49,6 @@ void following_pointers( // $ ast-def=sourceStruct1_ptr
int stackArray[2] = { source(), source() };
stackArray[0] = source();
sink(stackArray); // $ ast ir ir=49:25 ir=49:35 ir=50:19
sink(stackArray); // $ ast,ir
indirect_sink(stackArray); // $ ast ir=50:25 ir=50:35 ir=51:19
}

7
cpp/ql/test/library-tests/dataflow/dataflow-tests/dataflow-consistency.expected
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@@ -28,9 +28,10 @@ postWithInFlow
| BarrierGuard.cpp:49:6:49:6 | x [post update] | PostUpdateNode should not be the target of local flow. |
| BarrierGuard.cpp:60:7:60:7 | x [post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:22:9:22:20 | sourceArray1 [inner post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:28:22:28:23 | m1 [post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:50:3:50:12 | stackArray [inner post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:50:3:50:15 | access to array [post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:23:18:23:29 | sourceArray1 [inner post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:29:22:29:23 | m1 [post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:51:3:51:12 | stackArray [inner post update] | PostUpdateNode should not be the target of local flow. |
| clang.cpp:51:3:51:15 | access to array [post update] | PostUpdateNode should not be the target of local flow. |
| dispatch.cpp:60:3:60:14 | globalBottom [post update] | PostUpdateNode should not be the target of local flow. |
| dispatch.cpp:61:3:61:14 | globalMiddle [post update] | PostUpdateNode should not be the target of local flow. |
| dispatch.cpp:78:24:78:37 | call to allocateBottom [inner post update] | PostUpdateNode should not be the target of local flow. |

6
cpp/ql/test/library-tests/dataflow/dataflow-tests/test.cpp
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@@ -1,5 +1,5 @@
int source();
void sink(int); void sink(const int *); void sink(int **);
void sink(int); void sink(const int *); void sink(int **); void indirect_sink(...);
void intraprocedural_with_local_flow() {
int t2;
@@ -626,7 +626,7 @@ void test_def_via_phi_read(bool b)
use(buffer);
}
intPointerSource(buffer);
sink(buffer); // $ ast,ir
indirect_sink(buffer); // $ ast,ir
}
void test_static_local_1() {
@@ -692,7 +692,7 @@ void test_static_local_9() {
void increment_buf(int** buf) { // $ ast-def=buf ir-def=*buf ir-def=**buf
*buf += 10;
sink(buf); // $ SPURIOUS: ast,ir // should only be flow to the indirect argument, but there's also flow to the non-indirect argument
sink(buf); // $ SPURIOUS: ast
}
void call_increment_buf(int** buf) { // $ ast-def=buf

9
cpp/ql/test/library-tests/dataflow/dataflow-tests/test.ql
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@@ -34,7 +34,7 @@ module AstTest {
override predicate isSink(DataFlow::Node sink) {
exists(FunctionCall call |
call.getTarget().getName() = "sink" and
call.getTarget().getName() = ["sink", "indirect_sink"] and
sink.asExpr() = call.getAnArgument()
)
}
@@ -83,9 +83,12 @@ module IRTest {
}
override predicate isSink(DataFlow::Node sink) {
exists(FunctionCall call |
exists(FunctionCall call, Expr e | e = call.getAnArgument() |
call.getTarget().getName() = "sink" and
call.getAnArgument() in [sink.asExpr(), sink.asIndirectExpr()]
sink.asExpr() = e
or
call.getTarget().getName() = "indirect_sink" and
sink.asIndirectExpr() = e
)
}

13
cpp/ql/test/query-tests/Security/CWE/CWE-078/SAMATE/ExecTainted/ExecTainted.expected
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@@ -1,29 +1,16 @@
edges
| tests.cpp:26:15:26:23 | badSource indirection | tests.cpp:51:12:51:20 | call to badSource indirection |
| tests.cpp:26:32:26:35 | data indirection | tests.cpp:26:15:26:23 | badSource indirection |
| tests.cpp:26:32:26:35 | data indirection | tests.cpp:38:25:38:36 | strncat output argument |
| tests.cpp:33:34:33:39 | call to getenv indirection | tests.cpp:38:39:38:49 | environment indirection |
| tests.cpp:38:25:38:36 | strncat output argument | tests.cpp:26:15:26:23 | badSource indirection |
| tests.cpp:38:25:38:36 | strncat output argument | tests.cpp:26:15:26:23 | badSource indirection |
| tests.cpp:38:25:38:36 | strncat output argument | tests.cpp:51:22:51:25 | badSource output argument |
| tests.cpp:38:39:38:49 | environment indirection | tests.cpp:38:25:38:36 | strncat output argument |
| tests.cpp:51:12:51:20 | call to badSource indirection | tests.cpp:53:16:53:19 | data indirection |
| tests.cpp:51:22:51:25 | badSource output argument | tests.cpp:51:22:51:25 | data indirection |
| tests.cpp:51:22:51:25 | data indirection | tests.cpp:26:32:26:35 | data indirection |
| tests.cpp:51:22:51:25 | data indirection | tests.cpp:51:12:51:20 | call to badSource indirection |
nodes
| tests.cpp:26:15:26:23 | badSource indirection | semmle.label | badSource indirection |
| tests.cpp:26:15:26:23 | badSource indirection | semmle.label | badSource indirection |
| tests.cpp:26:32:26:35 | data indirection | semmle.label | data indirection |
| tests.cpp:33:34:33:39 | call to getenv indirection | semmle.label | call to getenv indirection |
| tests.cpp:38:25:38:36 | strncat output argument | semmle.label | strncat output argument |
| tests.cpp:38:25:38:36 | strncat output argument | semmle.label | strncat output argument |
| tests.cpp:38:39:38:49 | environment indirection | semmle.label | environment indirection |
| tests.cpp:51:12:51:20 | call to badSource indirection | semmle.label | call to badSource indirection |
| tests.cpp:51:22:51:25 | badSource output argument | semmle.label | badSource output argument |
| tests.cpp:51:22:51:25 | data indirection | semmle.label | data indirection |
| tests.cpp:53:16:53:19 | data indirection | semmle.label | data indirection |
subpaths
| tests.cpp:51:22:51:25 | data indirection | tests.cpp:26:32:26:35 | data indirection | tests.cpp:26:15:26:23 | badSource indirection | tests.cpp:51:12:51:20 | call to badSource indirection |
#select
| tests.cpp:53:16:53:19 | data | tests.cpp:33:34:33:39 | call to getenv indirection | tests.cpp:53:16:53:19 | data indirection | This argument to an OS command is derived from $@, dangerously concatenated into $@, and then passed to system(string). | tests.cpp:33:34:33:39 | call to getenv indirection | user input (an environment variable) | tests.cpp:38:25:38:36 | strncat output argument | strncat output argument |

2
cpp/ql/test/query-tests/Security/CWE/CWE-078/semmle/ExecTainted/ExecTainted.expected
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@@ -45,8 +45,6 @@ edges
| test.cpp:186:47:186:54 | filename indirection | test.cpp:188:20:188:24 | flags indirection |
| test.cpp:187:11:187:15 | strncat output argument | test.cpp:188:11:188:17 | strncat output argument |
| test.cpp:187:18:187:25 | filename indirection | test.cpp:187:11:187:15 | strncat output argument |
| test.cpp:188:11:188:17 | strncat output argument | test.cpp:188:11:188:17 | strncat output argument |
| test.cpp:188:11:188:17 | strncat output argument | test.cpp:188:11:188:17 | strncat output argument |
| test.cpp:188:20:188:24 | flags indirection | test.cpp:188:11:188:17 | strncat output argument |
| test.cpp:194:9:194:16 | fread output argument | test.cpp:196:26:196:33 | filename indirection |
| test.cpp:196:10:196:16 | concat output argument | test.cpp:198:32:198:38 | command indirection |