CWE-467: Use of sizeof() on a Pointer Type
The code calls sizeof() on a pointer type, which can be an incorrect calculation if the programmer intended to determine the size of the data that is being pointed to.
How it's found
Use of sizeof() on a Pointer Type is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
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.
Vulnerable vs. safe
double *foo;...foo = (double *)malloc(sizeof(foo));double *foo;...foo = (double *)malloc(sizeof(*foo));Consequences
- 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.
Mitigations
- 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.
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is CWE-467?
The code calls sizeof() on a pointer type, which can be an incorrect calculation if the programmer intended to determine the size of the data that is being pointed to.
How do you find Use of sizeof() on a Pointer Type?
Use of sizeof() on a Pointer Type is a specific, narrowly defined instance of a broader pattern. Testers confirm it with targeted code review and a proof-of-concept input that exercises the exact code path this weakness describes.
What is the impact of CWE-467?
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.
Does TurboPentest test for Use of sizeof() on a Pointer Type?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
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Written and reviewed by
Michel Chamberland - Founder & CEO, IntegSec
CISSP, OSCP, OSCE, CEH, GIAC, CCSK · 20+ years in offensive security
Michel has spent 20+ years on offensive security teams including IBM X-Force Red and Trustwave SpiderLabs, leading penetration tests, red team engagements, and breach response for Fortune 500 customers. He is the founder of IntegSec and the architect of TurboPentest.
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