1111
The code calls sizeof() on a malloced pointer type, which always returns the wordsize/8. This can
produce an unexpected result if the programmer intended to determine how much memory has
been allocated.
Extended Description
The use of sizeof() on a pointer can sometimes generate useful information. An obvious case is to
find out the wordsize on a platform. More often than not, the appearance of sizeof(pointer) indicates
a bug.
Relationships
The table(s) below shows the weaknesses and high level categories that are related to this
weakness. These relationships are defined as ChildOf, ParentOf, MemberOr and give insight to
similar items that may exist at higher and lower levels of abstraction. In addition, relationships such
as PeerOf and CanAlsoBe are defined to show similar weaknesses that may want to be explored.
Relevant to the view "Research Concepts" (CWE-1000)
Nature Type ID Name Page
ChildOf 131 Incorrect Calculation of Buffer Size 355
Weakness Ordinalities
Primary :
Applicable Platforms
Language : C (Prevalence = Undetermined)
Language : C++ (Prevalence = Undetermined)
Likelihood Of Exploit
High
Common Consequences
Scope Impact Likelihood
Integrity
Confidentiality
Modify Memory
Read Memory
This error can often cause one to allocate a buffer that is
much smaller than what is needed, leading to resultant
weaknesses such as buffer overflows.
Detection Methods
Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST),
can find some instances of this weakness by analyzing source code (or binary/compiled code)
without having to execute it. Typically, this is done by building a model of data flow and control
flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input)
with "sinks" (destinations where the data interacts with external components, a lower layer such
as the OS, etc.)
Effectiveness = High
Potential Mitigations
Phase: Implementation
Use expressions such as "sizeof(*pointer)" instead of "sizeof(pointer)", unless you intend to run
sizeof() on a pointer type to gain some platform independence or if you are allocating a variable
on the stack.
Demonstrative Examples
CWE Version 4.14
CWE-467: Use of sizeof() on a Pointer Type
CWE-467: Use of sizeof() on a Pointer Type