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Prevent division/modulo by zero in scripts.

Browse source 
Integral/floating-point division/modulo by zero in C++ is undefined
behavior, so to prevent such cases in a script from crashing Bro,
they're now reported as an error (with script location information) and
the event handler in which it occurred returns immediately.
This commit is contained in:
Jon Siwek 2013-09-20 16:36:00 -05:00
parent 4e2e690bff
commit 1750e351c4
3 changed files with 82 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

43
src/Expr.cc
View file

@ -779,9 +779,48 @@ Val* BinaryExpr::Fold(Val* v1, Val* v2) const
case EXPR_SUB: DO_FOLD(-); break; case EXPR_SUB: DO_FOLD(-); break;
case EXPR_REMOVE_FROM: DO_FOLD(-); break; case EXPR_REMOVE_FROM: DO_FOLD(-); break;
case EXPR_TIMES: DO_FOLD(*); break; case EXPR_TIMES: DO_FOLD(*); break;
case EXPR_DIVIDE: DO_FOLD(/); break; case EXPR_DIVIDE:
{
if ( is_integral )
{
if ( i2 == 0 )
reporter->ExprRuntimeError(this, "division by zero");
i3 = i1 / i2;
}
else if ( is_unsigned )
{
if ( u2 == 0 )
reporter->ExprRuntimeError(this, "division by zero");
u3 = u1 / u2;
}
else
{
if ( d2 == 0 )
reporter->ExprRuntimeError(this, "division by zero");
d3 = d1 / d2;
}
}
break;
case EXPR_MOD:
{
if ( is_integral )
{
if ( i2 == 0 )
reporter->ExprRuntimeError(this, "modulo by zero");
i3 = i1 % i2;
}
else if ( is_unsigned )
{
if ( u2 == 0 )
reporter->ExprRuntimeError(this, "modulo by zero");
u3 = u1 % u2;
}
else
Internal("bad type in BinaryExpr::Fold");
}
break;
case EXPR_MOD: DO_INT_FOLD(%); break;
case EXPR_AND: DO_INT_FOLD(&&); break; case EXPR_AND: DO_INT_FOLD(&&); break;
case EXPR_OR: DO_INT_FOLD(||); break; case EXPR_OR: DO_INT_FOLD(||); break;

5
testing/btest/Baseline/core.div-by-zero/out Normal file
View file

@ -0,0 +1,5 @@
expression error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/core.div-by-zero/div-by-zero.bro, line 6: division by zero [a / b]
expression error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/core.div-by-zero/div-by-zero.bro, line 11: division by zero [a / b]
expression error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/core.div-by-zero/div-by-zero.bro, line 16: division by zero [a / b]
expression error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/core.div-by-zero/div-by-zero.bro, line 21: modulo by zero [a % b]
expression error in /Users/jsiwek/Projects/bro/bro/testing/btest/.tmp/core.div-by-zero/div-by-zero.bro, line 26: modulo by zero [a % b]

36
testing/btest/core/div-by-zero.bro Normal file
View file

@ -0,0 +1,36 @@
# @TEST-EXEC: bro -b %INPUT >out 2>&1
# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
event div_int(a: int, b: int)
{
print a / b;
}
event div_count(a: count, b: count)
{
print a / b;
}
event div_double(a: double, b: double)
{
print a / b;
}
event mod_int(a: int, b: int)
{
print a % b;
}
event mod_count(a: count, b: count)
{
print a % b;
}
event bro_init()
{
event div_int(10, 0);
event div_count(10, 0);
event div_double(10.0, 0.0);
event mod_int(10, 0);
event mod_count(10, 0);
}