Some insecure common C Functions

Some insecure common C functions-general Linux technology-Linux programming and kernel information. The following is a detailed description. 1 gets ()
Gets () has the BufferOverflow problem because it cannot specify the size of the buffer to be copied. Specify the Buffer Size by using the substitution function, or use fgets ().

2 scanf ()
Use scanf () instead of scanf_s () or sscanf () as a replacement function.

3 strcpy ()
Strcpy () does not check the Size of the Buffer before copy, so there is a Buffer Overflow problem. Be sure to use functions with high security according to strncpy_s (), strcpy_s (), strncpy () and other environments.

In addition, even if a function with high security is used, Buffer Overflow may also occur due to usage reasons. Pay attention to the following points. Do not perform Buffer Size in strcpy_s () or strncpy_s? .

4 strcat ()
Strcat () does not check the Buffer length, so there is a BufferOverflow problem. Please use according to strncat_s ()? Strcat_s (), strncat (), and other functions with high security. In addition, even if a function with high security is used, BufferOverflow is generated due to usage reasons. Pay attention to the following points. What are the Buffer lengths of strcat_s () and strncat_s? .

5 sprintf ()
Use the highly secure functions prepared by sprintf_s () and snprintf () respectively. In addition, BufferOverflow in very old UNIX/Linux systems, especially in linux libc4's earlier versions, such as snprintf (), is actually unavoidable, so please note.