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How does buffer cache work?
In SQL Server, the buffer cache is the memory that allows you to query frequently accessed data quickly. When data is written to or read from a SQL Server database, the buffer manager copies it into the buffer cache (aka the buffer pool).
Where are kernel buffers stored?
The kernel buffers. As the instrumented kernel intercepts events, it stores them in a circular linked list of buffers. As each buffer fills, the instrumented kernel sends a signal to the data-capturing program that the buffer is ready to be read.
Why do we use buffer cache?
The buffer cache serializes access to the disk blocks, just as locks serialize access to in- memory data structures. Like the operating system as a whole, the buffer cache’s fun- damental purpose is to enable safe cooperation between processes.
What’s the difference between a user and a kernel buffer?
There is a very big difference between the two buffers, one is kernel buffer and the other is the user buffer. So, what basically happens when you do a I/O is that the buffer from the user space is copied into a buffer in the kernel space. The function copy_from_user () does this task.
Is the kernel protected from buffer overflow attacks?
No. Kernel space is protected on most architectures by processor and, unless there is an error in operating system, the attempt to write there would result in termination of process. The buffer overflow attack (usually) overwrites the return address of function which breaks the control flow in hands of attacker.
How to avoid stack overflow with user space buffer?
In kernel if a non-valid address is accessed then the system will panic immediately, so the function copy_from_user does the task of mapping the user space address and the kernel space address and checks if the address is accessible or not. If not then it simply returns EFAULT (bad address). Thanks for contributing an answer to Stack Overflow!
What happens when a buffer overflow is triggered in a process?
That means it can’t access the memory of other processes, or unallocated memory, or kernel memory. So even if an attacker triggers a buffer overflow in a process and is able to execute arbitrary code in that process’s context, that doesn’t give the attacker kernel-level access. There is one way out: processes can make system calls.