...
Do
...
not
...
use
...
the
...
same
...
variable
...
name
...
in
...
two
...
scopes
...
where
...
one
...
scope
...
is
...
contained
...
in
...
another.
...
For
...
example
...
- No
...
- other
...
- variable
...
- should
...
- share
...
- the
...
- name
...
- of
...
- a
...
- global
...
- variable
...
- if
...
- the
...
- other
...
- variable
...
- is
...
- in
...
- a
...
- subscope
...
- of
...
- the
...
- global
...
- variable.
...
- A
...
- block
...
- should
...
- not
...
- declare
...
- a
...
- variable
...
- with
...
- the
...
- same
...
- name
...
- as
...
- a
...
- variable
...
- declared
...
- in
...
- any
...
- block
...
- that
...
- contains
...
- it.
...
Reusing
...
variable
...
names
...
leads
...
to
...
programmer
...
confusion
...
about
...
which
...
variable
...
is
...
being
...
modified.
...
Additionally,
...
if
...
variable
...
names
...
are
...
reused,
...
generally
...
one
...
or
...
both
...
of
...
the
...
variable
...
names
...
are
...
too
...
generic.
...
Noncompliant
...
Code
...
Example
...
This
...
noncompliant
...
code
...
example
...
declares
...
the
...
msg
...
identifier
...
at
...
the
...
start
...
of
...
the
...
compilation
...
unit
...
(with
...
file
...
scope)
...
and
...
reuses
...
the
...
same
...
identifier
...
to
...
declare
...
a
...
character
...
array
...
local
...
to
...
the
...
report_error()
...
function.
...
Consequently,
...
the
...
programmer
...
unintentionally
...
copies
...
a
...
string
...
to
...
the
...
locally
...
declared
...
msg
...
array
...
within
...
the
...
report_error()
...
function,
...
failing
...
to
...
initialize
...
the
...
global
...
msg
...
variable
...
and
...
resulting
...
in
...
a
...
potential
...
buffer
...
overflow.
| Code Block | ||||
|---|---|---|---|---|
| =
| |||
}
char msg[100];
void report_error(const char *error_msg) {
char msg[80];
/* ... */
strncpy(msg, error_msg, sizeof(msg));
return;
}
int main(void) {
char error_msg[80];
/* ... */
report_error(error_msg);
/* ... */
}
|
Compliant Solution
This compliant solution uses different, more descriptive variable names.
| Code Block | ||
|---|---|---|
| ||
{mc} ANKUR {mc} {code} h2. Compliant Solution This compliant solution uses different, more descriptive variable names. {code:bgColor=#ccccff} char system_msg[100]; void report_error(const char *error_msg) { char default_msg[80]; /* ... */ if (error_msg) strncpy(system_msg, error_msg, sizeof(system_msg)); else strncpy(system_msg, default_msg, sizeof(system_msg)); system_msg[ sizeof(system_msg) - 1] = '\0'; return; } int main(void) { char error_msg[80]; /* ... */ report_error(error_msg); /* ... */ } {code} |
When
...
the
...
block
...
is
...
small,
...
the
...
danger
...
of
...
reusing
...
variable
...
names
...
is
...
mitigated
...
by
...
the
...
visibility
...
of
...
the
...
immediate
...
declaration.
...
Even
...
in
...
this
...
case,
...
however,
...
variable
...
name
...
reuse
...
is
...
not
...
desirable.
...
By
...
using
...
different
...
variable
...
names
...
globally
...
and
...
locally,
...
the
...
compiler
...
forces
...
the
...
developer
...
to
...
be
...
more
...
precise
...
and
...
descriptive
...
with
...
variable
...
names.
...
Risk
...
Assessment
...
Reusing
...
a
...
variable
...
name
...
in
...
a
...
subscope
...
can
...
lead
...
to
...
unintentionally
...
referencing
...
an
...
incorrect
...
variable.
...
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
DCL01-C | low | unlikely | medium | P2 | L3 |
Automated Detection
The LDRA tool suite Version 7.6.0
...
can
...
detect
...
violations
...
of
...
this
...
recommendation.
...
Splint
...
Version
...
3.1.1
...
can
...
detect
...
violations
...
of
...
this
...
recommendation.
...
Compass/ROSE
...
can
...
detect
...
violations
...
of
...
this
...
recommendation.
...
Klocwork
...
Version
...
8.0.4.16
...
can
...
detect
...
violations
...
of
...
this
...
rule
...
with
...
the
...
IF_MULTI_DECL
...
,
...
IF_MULTI_DEF
...
,
...
and
...
IF_MULTI_KIND
...
checkers.
...
Related
...
Vulnerabilities
...
Search
...
for
...
vulnerabilities
...
resulting
...
from
...
the
...
violation
...
of
...
this
...
rule
...
on
...
the
...
...
...
.
Other Languages
This rule appears in the C++ Secure Coding Standard as DCL01-CPP.
...
...
...
...
...
...
...
...
.
This rule appears in the Java Secure Coding Standard as SCP03-J.
...
...
...
...
...
.
References
| Wiki Markup |
|---|
\[[ISO/IEC 9899:1999|AA. C References#ISO/IEC 9899-1999]\] Section 5.2.4.1, "Translation limits"
\[[MISRA 04|AA. C References#MISRA 04]\] Rule 5.2 |
...
...