sprintf
Prototype
This function writes a formatted string to the array pointed to by str
. The format
argument is a string that specifies how the subsequent arguments are formatted. The ...
indicates that the function can take a variable number of arguments.
Vulnerable example
In this code, the sprintf
function is used to copy the contents of argv[1]
(a command line argument) into the buffer
array, which has a fixed size of 8 bytes. If the length of argv[1]
is greater than 8 bytes, it will overwrite memory beyond the bounds of the buffer
array, potentially causing a buffer overflow.
Prevent
To prevent this vulnerability, the program should ensure that the length of the data being written to the buffer is within the bounds of the buffer's size. For example, the following code uses snprintf
(a variant of sprintf
that includes a size parameter) to ensure that the data being written to the buffer does not exceed its size:
Using snprintf
ensures that the data written to the buffer
array does not exceed its size, and prevents a buffer overflow vulnerability.
Last updated