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Fix seg fault on trying to type-cast invalid/nil Broker::Data

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This situation now throws a runtime expression exception instead of
crashing on null pointer access.
This commit is contained in:
Jon Siwek 2018-08-15 11:00:20 -05:00
parent 0e6913fba0
commit f336c8c710
6 changed files with 28 additions and 4 deletions
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5
CHANGES
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@ -1,4 +1,9 @@
2.5-842 | 2018-08-15 11:00:20 -0500
* Fix seg fault on trying to type-cast invalid/nil Broker::Data
(Jon Siwek, Corelight)
2.5-841 | 2018-08-14 16:45:09 -0500
* BIT-1798: fix PPTP GRE tunnel decapsulation (Jon Siwek, Corelight)

2
VERSION
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@ -1 +1 @@
2.5-841
2.5-842

9
src/Expr.cc
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@ -16,6 +16,8 @@
#include "Trigger.h"
#include "IPAddr.h"
#include "broker/Data.h"
const char* expr_name(BroExprTag t)
{
static const char* expr_names[int(NUM_EXPRS)] = {
@ -5503,11 +5505,16 @@ Val* CastExpr::Eval(Frame* f) const
}
ODesc d;
d.Add("cannot cast value of type '");
d.Add("invalid cast of value with type '");
v->Type()->Describe(&d);
d.Add("' to type '");
Type()->Describe(&d);
d.Add("'");
if ( same_type(v->Type(), bro_broker::DataVal::ScriptDataType()) &&
! v->AsRecordVal()->Lookup(0) )
d.Add(" (nil $data field)");
Unref(v);
reporter->ExprRuntimeError(this, "%s", d.Description());
return 0; // not reached.

8
src/Val.cc
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@ -3632,6 +3632,10 @@ Val* cast_value_to_type(Val* v, BroType* t)
if ( same_type(v->Type(), bro_broker::DataVal::ScriptDataType()) )
{
auto dv = v->AsRecordVal()->Lookup(0);
if ( ! dv )
return 0;
return static_cast<bro_broker::DataVal *>(dv)->castTo(t);
}
@ -3654,6 +3658,10 @@ bool can_cast_value_to_type(const Val* v, BroType* t)
if ( same_type(v->Type(), bro_broker::DataVal::ScriptDataType()) )
{
auto dv = v->AsRecordVal()->Lookup(0);
if ( ! dv )
return false;
return static_cast<const bro_broker::DataVal *>(dv)->canCastTo(t);
}

6
testing/btest/Baseline/language.type-cast-error-dynamic/output
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@ -1,2 +1,4 @@
expression error in /home/robin/bro/lang-ext/testing/btest/.tmp/language.type-cast-error-dynamic/type-cast-error-dynamic.bro, line 11: cannot cast value of type 'count' to type 'string' [a as string]
expression error in /home/robin/bro/lang-ext/testing/btest/.tmp/language.type-cast-error-dynamic/type-cast-error-dynamic.bro, line 11: cannot cast value of type 'record { a:addr; b:port; }' to type 'string' [a as string]
expression error in /Users/jon/projects/bro/bro/testing/btest/.tmp/language.type-cast-error-dynamic/type-cast-error-dynamic.bro, line 11: invalid cast of value with type 'count' to type 'string' [a as string]
expression error in /Users/jon/projects/bro/bro/testing/btest/.tmp/language.type-cast-error-dynamic/type-cast-error-dynamic.bro, line 11: invalid cast of value with type 'record { a:addr; b:port; }' to type 'string' [a as string]
expression error in /Users/jon/projects/bro/bro/testing/btest/.tmp/language.type-cast-error-dynamic/type-cast-error-dynamic.bro, line 11: invalid cast of value with type 'record { data:opaque of Broker::Data; }' to type 'string' (nil $data field) [a as string]
data is string, F

2
testing/btest/language/type-cast-error-dynamic.bro
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@ -18,6 +18,8 @@ event bro_init()
cast_to_string(42);
cast_to_string(x);
cast_to_string(Broker::Data());
print "data is string", Broker::Data() is string;
}