codeql/cpp/ql/src/Critical/OverflowCalculated.ql at codeql-cli/latest · github/codeql · GitHub

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/**

* @name Buffer not sufficient for string

* @description A buffer allocated using 'malloc' may not have enough space for a string that is being copied into it. The operation can cause a buffer overrun. Make sure that the buffer contains enough room for the string (including the zero terminator).

* @kind problem

* @id cpp/overflow-calculated

* @problem.severity warning

* @security-severity 9.8

* @tags reliability

* security

* external/cwe/cwe-131

* external/cwe/cwe-120

import cpp

import semmle.code.cpp.ir.dataflow.DataFlow

import semmle.code.cpp.models.interfaces.Allocation

predicate spaceProblem(FunctionCall append, string msg) {

exists(

AllocationExpr malloc, StrlenCall strlen, AddExpr add, FunctionCall insert, Variable buffer

add.getAChild() = strlen and

exists(add.getAChild().getValue()) and

DataFlow::localExprFlow(add, malloc.getSizeExpr()) and

buffer.getAnAccess() = strlen.getStringExpr() and

(

insert.getTarget().hasGlobalOrStdName("strcpy") or

insert.getTarget().hasGlobalOrStdName("strncpy")

) and

(

append.getTarget().hasGlobalOrStdName("strcat") or

append.getTarget().hasGlobalOrStdName("strncat")

) and

malloc.getASuccessor+() = insert and

insert.getArgument(1) = buffer.getAnAccess() and

insert.getASuccessor+() = append and

msg =

"This buffer only contains enough room for '" + buffer.getName() + "' (copied on line " +

insert.getLocation().getStartLine().toString() + ")"

)

}

from Expr problem, string msg

where spaceProblem(problem, msg)

select problem, msg

codeql/cpp/ql/src/Critical/OverflowCalculated.ql at codeql-cli/latest · github/codeql · GitHub

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