Summary:
This diff extends inferbo's domain to include closure values. The goal of this extension is to
follow missing semantics where closures are handled as values, for example, a closure is assigned to
an object field, then it is got later to call.
Due to the bottom-up nature of the analyzer, sometimes we don't know which values are written in a
field, which is the same for the other non-closure values.
Reviewed By: ezgicicek
Differential Revision: D23932186
fbshipit-source-id: 4a575d0de
Summary: This diff adds trace field for autoreleasepool size. Unlike to the other checkers, eg inferbo and operation cost, the autoreleasepool size checker should have traces for constants.
Reviewed By: ezgicicek
Differential Revision: D23678084
fbshipit-source-id: 35e6cf5f5
Summary:
Two issues are fixed
1. For this diff, when the condition `curr_langauge_is Java` is removed in some part of the analysis, some c bufferoverrun tests are broken. This is fixed in this diff by inspecting if we are dealing with a `Size` alias referring to an `objc_internal_collection_array`.
2. Previously, when we are modifying mutable array in a loop, e.g. adding element to the array or removing element from the array, we are unable to give an estimable size of the array after exiting the loop. This is now fixed, and the corresponding FPs are resolved.
Reviewed By: skcho
Differential Revision: D23342350
fbshipit-source-id: 200f5261c
Summary:
In the previous diffs, we implement enumerator in order to estimate the cost of for-each loop in ObjC, but when we have FP case when enumerator is used not in for-each loop. For example, the following code has top cost before the fix.
```
void nsarray_enumerator_linear_FP(NSArray* array) {
id obj;
NSInteger sum = 0;
NSEnumerator* enumerator = [array objectEnumerator];
while (obj = [enumerator nextObject]) {
sum += (NSInteger)obj;
}
}
```
Reviewed By: skcho
Differential Revision: D23294895
fbshipit-source-id: 50c7b359f
Summary:
As title.
This diff is co-authored by SungKeun Cho and me.
facebook
This diff is co-authored by skcho and me.
Original comments from skcho
"For the record:
1. Rory and I tried to write models for ObjC iterator.
2. We could not use Java's iterator semantics: In Java's, `hasNext` returns the size of collection, rather than a boolean, and which is used as a control variable. On the other hand, in ObjC, it calls only `nextObject`, not calling `hasNext`, and the return value of which is being checked as `null`.
3. We added an artificial field `objc_iterator_offset` to keep the index of the iterator, and the models added in this diff are handling that integer value.
A problem is that `array.objc_iterator_offset` is not included in the control variables, since the condition of the loop is `nextObject() != null` that does not include the iterator offset. We need to make `array.objc_iterator_offset` as a control variable, by changing the part collecting control variables.
"
Reviewed By: ezgicicek, skcho
Differential Revision: D22944278
fbshipit-source-id: 7e71b79c1
Summary: D17500386 had added the ability to give symbolic values on functions returning exceptions. However, this might cause FPs or cryptic complexity reports (especially with subclass heuristics). This diff aims to revert it back.
Reviewed By: skcho
Differential Revision: D22764266
fbshipit-source-id: 1615544d8
Summary:
This diff tries to support a specific form of linked list iteration in Java.
```
while (p != null) {
p = p.getNext();
}
```
This example was a constant cost before because the cost checker could not detect that it is an iteration on a linked list.
The heuristic this diff implemented is:
(1) `p = p.getNext()`: It tries to find this specific form of assignment. Then, it increments `p.linked_list_index` by 1. Note that `linked_list_index` is a virtual field for keeping an index in the linked list. Its initial value is always 0.
(2) At `p != null`, it tries to prune the value of `p.linked_list_index`: the upper-bound of `p.linked_list_index` is pruned by `<= p.linked_list_length`. Here again, `p.linked_list_length` is also a virtual field to denote the length of the linked list.
Reviewed By: ezgicicek
Differential Revision: D22234892
fbshipit-source-id: 2fee176bb
Summary:
In inferbo's domain, `Loc.t` and `Symb.SymbolPath.partial` are defined with the same *field abstraction*. The depth of appended fields were limited in both of them exactly in the same way, e.g. `x.*.field`. Problem is that the implementation related
to the field abstraction are duplicated in their code, which had been synchronized manually. This diff avoids the duplication by adding a `BufferOverrunField.t`.
Reviewed By: ezgicicek
Differential Revision: D21743728
fbshipit-source-id: 4b01d027c
Summary:
This diff revises how to handle the unknown location in inferbo in two ways:
* stop appending field to the `Unknown` location, e.g. `Unknown.x.a` is evaluated to `Unknown`
* redesign the abstract of multiple locations, like `Bottom` < `Unknown` < `Known` locations
I am doing them in one diff since applying only one of them showed bad results.
Background: `Unknown` was adopted for abstracting all unknown concrete locations, so we could avoid missing semantics of assignments to unknown locations. We tried to keep soundness. However, it brought some other problems related to precision and performance.
1. Sometimes especially when Inferbo failed to reason precise pointer values, `Unknown` may point to many other abstract locations.
2. At that time, value assignments to `*Unknown` makes the situation worse: many abstract locations are updated with imprecise values.
This problem harmed not only its precision, but also its performance since it introduced more location entries in the abstract memory.
Reviewed By: jvillard
Differential Revision: D21017789
fbshipit-source-id: 0bb6bd8b5
Summary:
This diff distinguishes array declaration and size-setting in trace. For example, when there is an
assume statement on an array size, the array size can be pruned to another value. In which case, we
want to see "Set array size" in the trace, instead of "Array declaration".
Reviewed By: jvillard
Differential Revision: D20914930
fbshipit-source-id: 0253fb69e
Summary:
A java byte is not a short and a java character is not a C character. Fix those types by mapping them to what the spec ordains.
An extra advantage is that this establishes a bijection between java types and their project in the `sil` type system, so pretty printing in Java mode can actually be made to work.
Reviewed By: mityal
Differential Revision: D20330525
fbshipit-source-id: 00ac2294b
Summary:
This ignores the error memory status (e.g. when condition expression is evaluated to bottom), in
order to keep analyze following code.
```
if ( e ) // e is evaluated to bottom due to a problem of Inferbo {
... // code here was not analyzed before
}
```
Reviewed By: ezgicicek
Differential Revision: D20067434
fbshipit-source-id: a1713722c
Summary:
In Inferbo, the bottom memory is introduced when a node is unreachable by pruning, i.e.
`[[e]] <= [0,0]` on `prune(e)`. This diff distinguishes whether `[[e]]` is `[0,0]` (unreachable)
or bottom (it could not evaluate `e` by some unknown reasons).
Reviewed By: ezgicicek
Differential Revision: D19902046
fbshipit-source-id: 7706017d6
Summary: This diff makes the taint analysis in Inferbo inter-procedural: adding symbolic taint values and substitute them at function call statements.
Reviewed By: ezgicicek
Differential Revision: D19411022
fbshipit-source-id: 4ff9a590a
Summary:
This diff introduces two issue types: `BUFFER_OVERRUN_T1` and `INFERBO_ALLOC_IS_TAINTED`, which
denotes tainted values are used in array accesses and memory allocations, respectively.
Note that the taint analysis is intra-procedural for now.
Reviewed By: ezgicicek
Differential Revision: D19410536
fbshipit-source-id: af85148ec
Summary:
This diff adds a taint domain in Inferbo. The taint value will be used to find vulnerable array
accesses in the following diffs.
Reviewed By: ezgicicek
Differential Revision: D19391028
fbshipit-source-id: 566b4c0fe
Summary:
This diff gets global constant array values from their initializers. The `find_global_array` function is
added to memory domain, which finds values of global array locations during the ondemand value
generation.
Reviewed By: ngorogiannis
Differential Revision: D19300143
fbshipit-source-id: 7b0b84c42
Summary:
Inferbo analyzed some program points unreachable incorrectly, because of unsound semantics of band
operator, which did not handle the case when given parameters are pointer values.
Reviewed By: ngorogiannis
Differential Revision: D19392705
fbshipit-source-id: dd590508c
Summary:
This diff revises the generation of unknown value. If the type of the unknown value generating is
int, it does not add the "Unknown" pointer/array value.
Reviewed By: ngorogiannis
Differential Revision: D19392696
fbshipit-source-id: e1b3c9a3a
Summary:
This diff avoids that `array_sizeof` returns bottom value when given Java enum values, which
introduced unreachable code inadvertently.
Reviewed By: ngorogiannis
Differential Revision: D19409077
fbshipit-source-id: 2816fd995
Summary:
This diff does a refactoring on the function that gets summary from DB,
`get_proc_summary_and_formals`.
* It separates the function into `get_summary` and `get_formals`, and
* renames `Checker.get_proc_summary` to `get_checks_summary`
Reviewed By: ngorogiannis
Differential Revision: D19300136
fbshipit-source-id: d28eaf16d
Summary:
This diff updates the relation between iterator (offset) and integer value not only at
assignments (`x += 1`), but also at function calls (`foo()`) that increase integer values by one in
their side effects.
Reviewed By: ezgicicek
Differential Revision: D19163214
fbshipit-source-id: 47e52f939
Summary: This diff extends the domain to express the relation between iterator's offset and integer value.
Reviewed By: ezgicicek
Differential Revision: D19143670
fbshipit-source-id: 6223bc934
Summary:
Inferbo does not use the external relational domains, apron and elina. At some point, the parts of
inferbo using them were broken and they do not seem to be fixed easily in the near future. Let's
remove them and keep the code base cleaner.
Reviewed By: jvillard
Differential Revision: D19022905
fbshipit-source-id: e0eafe79f
Summary:
This exposes a more general interface to other modules, at the cost of
hiding the fact that it won't deal with all binary operations with equal
precision.
Reviewed By: ezgicicek
Differential Revision: D18908095
fbshipit-source-id: 0c0653bb6
Summary: Another dead flag that one could mistakenly think is accurate.
Reviewed By: dulmarod
Differential Revision: D18573925
fbshipit-source-id: 129a9cff5
Summary: This diff get static value with `EMPTY` field from class initializer.
Reviewed By: ngorogiannis
Differential Revision: D18616588
fbshipit-source-id: 26414c9b2
Summary: Following D18351867, this diff adds more size alias: when initial array size is one.
Reviewed By: ezgicicek
Differential Revision: D18530598
fbshipit-source-id: 26d57fe30
Summary:
This diff avoids unqualified variables by `ItvUpdatedBy` are qualified later. For example,
```
z = x & y;
z = z + 1;
```
While `z` should not be selected as a control variable, it wasn't, because it was qualified by the addition. This pattern introduces FPs in many cases.
Reviewed By: ngorogiannis
Differential Revision: D18505894
fbshipit-source-id: 13aec3008
Summary: Sometimes there is a code like `for(int i = 1; i < x; i++){ l.add(); }`, where the first element in a list is addressed specifically. This case was not analyzed precisely, because the alias value is added only when `i` is initialized by 0 by heuristic. This diff extends the heuristic, so it adds a size alias between `i` and `l.size()` when `i` is initialized by 0 or 1.
Reviewed By: ezgicicek
Differential Revision: D18351867
fbshipit-source-id: e7d19a4ec
Summary:
This diff extends the alias domain, so each variable can have multiple aliases.
It changed `KeyLhs` can be mapped to multiple alias targets in the `AliasMap` domain:
```
before : KeyLhs.t -> KeyRhs.t * AliasTarget.t
after : KeyLhs.t -> KeyRhs.t -> AliasTarget.t
```
Reviewed By: ezgicicek
Differential Revision: D18062178
fbshipit-source-id: b325a6055
Summary:
It extracts RHS of alias from `AliasTarget.t`, so it changes the `AliasMap` domain:
```
before : KeyLhs.t -> AliasTarget.t // AliasTarget.t includes KeyRhs.t
after : KeyLhs.t -> KeyRhs.t * AliasTarget.t
```
Reviewed By: ezgicicek
Differential Revision: D18299537
fbshipit-source-id: 1446580a8
Summary: The way `<=` is used in `AbstractDomain` prevents infix use and forces bracketing it everywhere. Replace with simple `leq`.
Reviewed By: jvillard
Differential Revision: D18201854
fbshipit-source-id: 8175224e4
Summary:
This diff adds SafeInvertedMap, which is similar to InvertedMap but it
guarantees that there is no top elements in the tree of the map.
Reviewed By: ezgicicek
Differential Revision: D18062174
fbshipit-source-id: 2fbc51f31
Summary:
This diff introduces inequality for the iterator alias target, as we
did for the size target before.
Reviewed By: ezgicicek
Differential Revision: D17879208
fbshipit-source-id: cc2f6a723
Summary:
This diff extends the alias domain to analyze loop with list comprehensions form in Java precisely.
```
list2 = new List();
for (Element e : list1) {
list2.add(e);
}
```
1. `IteratorOffset` is a relation between a iterator offset and a length of another array. For example, in the above example, after n-times of iterations, the offset of the iterator (if it exists) and the length of `list2` are the same as `n`.
2. `IteratorHasNext` is a relation between iterator and its `hasNext` result.
3. At the conditional nodes, it prunes the alias list length of `list2` by that of `list1`.
* if `hasNext(list1's iterator)` is true, `list2`'s length is pruned by `< list1's length`
* if `hasNext(list1's iterator)` is false, `list2`'s length is pruned by `= list1's length`
Reviewed By: ezgicicek
Differential Revision: D17667128
fbshipit-source-id: 41fb23a45
Summary:
This diff generates a symbolic value when a function returns only
exceptions. Previously, the exception expression is evaluated to top,
thus it was propagated to other functions, which made those costs as
top. For preventing that situation, this diff changed:
* exception expressions are evaluated to bottom, and
* if callee's return value is bottom, it generates a symbolic value
for it.
Reviewed By: ezgicicek
Differential Revision: D17500386
fbshipit-source-id: 0fdcc710d
Sungkeun Cho
Qianyi Shu
Ezgi Çiçek
Josh Berdine
Nikos Gorogiannis
Jules Villard