Intel® Inspector User Guide for Linux* OS

ID 767796
Date 5/15/2022
Public

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Uninitialized Partial Memory Access

Occurs when a read instruction references a block (2-bytes or more) of memory where part of the block is uninitialized.

Problem type: Uninitialized partial memory access

ID

Code Location

Description

1

Allocation site

If present, represents the location and associated call stack from which the memory block containing the offending address was allocated.

2

Read

Represents the instruction and associated call stack responsible for the partial uninitialized access.

If no allocation or deallocation is associated with this problem, the memory address might be in stack space.

NOTE:

The offset, if shown in the Code Locations pane, represents the byte offset into the allocated buffer where the Uninitialized partial memory access occurred.

C Example

struct person
{
    unsigned char age;
    char firstInitial;
    char middleInitial;
    char lastInitial;
};
struct person *p1, *p2;
p1 = (struct person*) malloc(sizeof(struct person));
p2 = (struct person*) malloc(sizeof(struct person));
p1->firstInitial = 'c';
p1->lastInitial = 'o';
*p2 = *p1; // will result in partial uninitialized read
Fortran Example

type node
    character data1
    character data2
end type node
    
! Variables
type(node) :: a, b
    
a%data1 = "a"
b = a

NOTE:
Buffers created by system calls linking processes to shared memory are flagged as allocated memory, which means the Intel Inspector does not report an Uninitialized partial memory access on these buffers.

Possible Correction Strategies

Determine the correct initialization for the memory being accessed.