The correct approach is to always declare at least one more byte than you read. I think your problem is that you allocate the BUFFER_SIZE for the buffer and read the same BUFFER_SIZE into it. It means you read single byte form the given address. (underflow is to reach before its allocation) char* x = malloc(10) Īddress is position in memory, thread is part of process running sequence of code. Use an array to reach after its allocation, char* x = malloc(10) Using this flag the compiler add some boundaries check, to ensure you won't use a buffer to reach outside of its allocation. Sometimes due to code error, there is read or write from outside the buffer, such an error is usually hard to detect. Usually C compiler doesn't add boundaries check for memory access. What is address and thread? what is the flag to see the thread in colors on screen?Īnd why it says 'read of size 1 at address." ? If anyone can explain me in a general sense: READ of size 1 at 0圆020000000fb thread T0 However, when I set the BUFFER_SIZE very small, say = 10, and i use the -fsanitizer=address to check for memory leak. In other words, when more data (than was originally allocated to be stored) gets placed by a program or system process. As a result, the program attempting to write the data to the buffer overwrites adjacent memory locations. when I set the BUFFER_SIZE reasonably small (say, 42) which is not yet the end of the first line, it prints out some weird symbol at the end, but I guess it is some bug in my own code. A buffer overflow (or buffer overrun) occurs when the volume of data exceeds the storage capacity of the memory buffer. When I set the BUFFER_SIZE very large, I can get the first line. I am trying to write a function to open a file, read a BUFFER_SIZE, store the content in an array, then track the character '\n' (because I want to get each line of the input). I am at the very beginning of learning C.
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