Detecting slab memory corruption via SLUB debug
Memory corruption can occur due to various bugs or defects: Uninitialized Memory Reads (UMR), Use After Free (UAF), Use After Return (UAR), double-free, memory leakage, or illegal Out Of Bounds (OOB) accesses that attempt to work upon (read/write/execute) illegal memory regions. They're unfortunately a very common root cause of bugs. Being able to debug them is a key skill. Having already checked out a few ways to catch them (the detailed coverage of setting up and using KASAN and UBSAN in the previous chapter), let's now leverage the kernel's built-in SLUB debug features to catch these bugs!
As you will know, memory is dynamically allocated and freed via the kernel's engine – the page (or Buddy System) allocator. To mitigate serious wastage (internal fragmentation) issues that it can face, the slab allocator (or slab cache) is layered upon it, serving two primary tasks – providing fragments of pages...
