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[inferbo] Extend Simple alias domain

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Summary:
This diff extends the `Simple` alias domain to address Java's
temporary variables better.  It now has an additional field to denote
an alias temporary variable.

Reviewed By: jvillard

Differential Revision: D17421907

fbshipit-source-id: 8b8b47461
master
Sungkeun Cho 5 years ago committed by Facebook Github Bot
parent d073e80648
commit 2158090322
3 changed files with 53 additions and 15 deletions
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45
infer/src/bufferoverrun/bufferOverrunDomain.ml
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@ -713,7 +713,8 @@ module AliasTarget = struct
pruning values of program variables. For example, a C statement "if(x){...}" is translated to
"%r=load(x); if(%r){...}" in Sil. At the load statement, we record the alias between the
values of %r and x, then we can prune not only the value of %r, but also that of x inside the
if branch. The i field is to express "%r=load(x)+i".
if branch. The java_tmp field is an additional slot for keeping one more alias of temporary
variable in Java. The i field is to express "%r=load(x)+i".
"Empty relation": For pruning vector.length with vector::empty() results, we adopt a specific
relation between %r and v->elements, where %r=v.empty(). So, if %r!=0, v's array length
@ -726,7 +727,7 @@ module AliasTarget = struct
field is to express "%r=x.size()+i", which is required to follow the semantics of `Array.add`
inside loops precisely. *)
type t =
| Simple of {l: Loc.t; i: IntLit.t}
| Simple of {l: Loc.t; i: IntLit.t; java_tmp: Loc.t option}
| Empty of Loc.t
| Size of {l: Loc.t; i: IntLit.t; java_tmp: Loc.t option}
| Fgets of Loc.t
@ -740,16 +741,18 @@ module AliasTarget = struct
if IntLit.isnegative i then F.fprintf fmt "-%a" IntLit.pp (IntLit.neg i)
else F.fprintf fmt "+%a" IntLit.pp i
in
let java_tmp_pp fmt java_tmp = Option.iter java_tmp ~f:(F.fprintf fmt "=%a" Loc.pp) in
fun fmt -> function
| Simple {l; i} ->
| Simple {l; i; java_tmp} ->
Loc.pp fmt l ;
if not (IntLit.iszero i) then intlit_pp fmt i
if not (IntLit.iszero i) then intlit_pp fmt i ;
java_tmp_pp fmt java_tmp
| Empty l ->
F.fprintf fmt "empty(%a)" Loc.pp l
| Size {l; i; java_tmp} ->
F.fprintf fmt "size(%a)" Loc.pp l ;
if not (IntLit.iszero i) then intlit_pp fmt i ;
Option.iter java_tmp ~f:(F.fprintf fmt "=%a" Loc.pp)
java_tmp_pp fmt java_tmp
| Fgets l ->
F.fprintf fmt "fgets(%a)" Loc.pp l
| Top ->
@ -759,9 +762,9 @@ module AliasTarget = struct
let fgets l = Fgets l
let get_locs = function
| Size {l; java_tmp= Some tmp} ->
| Simple {l; java_tmp= Some tmp} | Size {l; java_tmp= Some tmp} ->
PowLoc.singleton l |> PowLoc.add tmp
| Simple {l} | Size {l; java_tmp= None} | Empty l | Fgets l ->
| Simple {l; java_tmp= None} | Size {l; java_tmp= None} | Empty l | Fgets l ->
PowLoc.singleton l
| Top ->
PowLoc.empty
@ -771,12 +774,13 @@ module AliasTarget = struct
let loc_map x ~f =
match x with
| Simple {l; i} ->
Option.map (f l) ~f:(fun l -> Simple {l; i})
| Simple {l; i; java_tmp} ->
let java_tmp = Option.bind java_tmp ~f in
Option.map (f l) ~f:(fun l -> Simple {l; i; java_tmp})
| Empty l ->
Option.map (f l) ~f:(fun l -> Empty l)
| Size {l; i; java_tmp} ->
let java_tmp = Option.value_map java_tmp ~default:None ~f in
let java_tmp = Option.bind java_tmp ~f in
Option.map (f l) ~f:(fun l -> Size {l; i; java_tmp})
| Fgets l ->
Option.map (f l) ~f:(fun l -> Fgets l)
@ -873,8 +877,17 @@ module AliasMap = struct
let store : Loc.t -> Ident.t -> t -> t =
fun l id x ->
if Language.curr_language_is Java && Loc.is_frontend_tmp l then
Option.value_map (find_id id x) ~default:x ~f:(fun tgt -> add (Key.of_loc l) tgt x)
if Language.curr_language_is Java then
if Loc.is_frontend_tmp l then
Option.value_map (find_id id x) ~default:x ~f:(fun tgt -> add (Key.of_loc l) tgt x)
else
match find_id id x with
| Some (AliasTarget.Simple {i; l= java_tmp})
when IntLit.iszero i && Loc.is_frontend_tmp java_tmp ->
add (Key.of_id id) (AliasTarget.Simple {l; i; java_tmp= Some java_tmp}) x
|> add (Key.of_loc java_tmp) (AliasTarget.Simple {l; i; java_tmp= None})
| _ ->
x
else x
@ -947,10 +960,12 @@ module Alias = struct
else a
| Exp.BinOp (Binop.PlusA _, Exp.Var id, Exp.Const (Const.Cint i))
| Exp.BinOp (Binop.PlusA _, Exp.Const (Const.Cint i), Exp.Var id) ->
lift_map (AliasMap.load id (AliasTarget.Simple {l= loc; i= IntLit.neg i})) a
lift_map
(AliasMap.load id (AliasTarget.Simple {l= loc; i= IntLit.neg i; java_tmp= None}))
a
|> lift_map (AliasMap.store_n ~prev:prev.map loc id i)
| Exp.BinOp (Binop.MinusA _, Exp.Var id, Exp.Const (Const.Cint i)) ->
lift_map (AliasMap.load id (AliasTarget.Simple {l= loc; i})) a
lift_map (AliasMap.load id (AliasTarget.Simple {l= loc; i; java_tmp= None})) a
|> lift_map (AliasMap.store_n ~prev:prev.map loc id (IntLit.neg i))
| _ ->
a
@ -1822,7 +1837,7 @@ module Mem = struct
let load_simple_alias : Ident.t -> Loc.t -> t -> t =
fun id loc -> load_alias id (AliasTarget.Simple {l= loc; i= IntLit.zero})
fun id loc -> load_alias id (AliasTarget.Simple {l= loc; i= IntLit.zero; java_tmp= None})
let load_empty_alias : Ident.t -> Loc.t -> t -> t =

22
infer/tests/codetoanalyze/java/bufferoverrun/Array.java
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@ -100,4 +100,26 @@ class Array {
x.add(0);
this.iterate_collection_Bad(x);
}
boolean b;
int zero_to_five() {
return b ? 0 : 5;
}
void prune_assign_exp_Good() {
int idx;
int[] arr = new int[5];
if ((idx = zero_to_five()) != 5) {
arr[idx] = 0;
}
}
void prune_assign_exp_Bad() {
int idx;
int[] arr = new int[3];
if ((idx = zero_to_five()) != 5) {
arr[idx] = 0;
}
}
}

1
infer/tests/codetoanalyze/java/bufferoverrun/issues.exp
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@ -6,6 +6,7 @@ codetoanalyze/java/bufferoverrun/Array.java, codetoanalyze.java.bufferoverrun.Ar
codetoanalyze/java/bufferoverrun/Array.java, codetoanalyze.java.bufferoverrun.Array.null_pruning1_Good():void, 2, CONDITION_ALWAYS_FALSE, no_bucket, WARNING, [Here]
codetoanalyze/java/bufferoverrun/Array.java, codetoanalyze.java.bufferoverrun.Array.null_pruning2_Bad():void, 4, BUFFER_OVERRUN_L1, no_bucket, ERROR, [<Length trace>,Array declaration,Array access: Offset: 10 Size: 5]
codetoanalyze/java/bufferoverrun/Array.java, codetoanalyze.java.bufferoverrun.Array.null_pruning2_Good_FP():void, 4, BUFFER_OVERRUN_L1, no_bucket, ERROR, [<Length trace>,Array declaration,Array access: Offset: 10 Size: 5]
codetoanalyze/java/bufferoverrun/Array.java, codetoanalyze.java.bufferoverrun.Array.prune_assign_exp_Bad():void, 4, BUFFER_OVERRUN_L2, no_bucket, ERROR, [<Offset trace>,Call,Assignment,Assignment,Assignment,Assignment,<Length trace>,Array declaration,Array access: Offset: [0, 4] Size: 3]
codetoanalyze/java/bufferoverrun/ArrayListTest.java, ArrayListTest.add_in_loop_bad():void, 5, BUFFER_OVERRUN_L1, no_bucket, ERROR, [<Length trace>,Array declaration,Array access: Offset: 6 Size: 5]
codetoanalyze/java/bufferoverrun/ArrayListTest.java, ArrayListTest.add_in_loop_by_param_bad(java.util.ArrayList):void, 5, BUFFER_OVERRUN_L1, no_bucket, ERROR, [<Offset trace>,Assignment,Array declaration,Assignment,<Length trace>,Parameter `b.elements[*]`,Assignment,Array declaration,Array access: Offset: b.length + 1 Size: b.length]
codetoanalyze/java/bufferoverrun/ArrayListTest.java, ArrayListTest.alloc_is_negative_bad():void, 2, INFERBO_ALLOC_IS_NEGATIVE, no_bucket, ERROR, [Allocation: Length: -1]

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