On Thu, 17 Sep 2020 15:36:38 +0200 Marco Elver wrote: > On Thu, 17 Sep 2020 at 15:26, Hillf Danton wrote: > > Tue, 15 Sep 2020 15:20:37 +0200 > > > From: Alexander Potapenko <glider@xxxxxxxxxx> > > > > > > This adds the Kernel Electric-Fence (KFENCE) infrastructure. KFENCE is a > > > low-overhead sampling-based memory safety error detector of heap > > > use-after-free, invalid-free, and out-of-bounds access errors. > > > > > > KFENCE is designed to be enabled in production kernels, and has near > > > zero performance overhead. Compared to KASAN, KFENCE trades performance > > > for precision. The main motivation behind KFENCE's design, is that with > > > enough total uptime KFENCE will detect bugs in code paths not typically > > > exercised by non-production test workloads. One way to quickly achieve a > > > large enough total uptime is when the tool is deployed across a large > > > fleet of machines. > > > > > > KFENCE objects each reside on a dedicated page, at either the left or > > > right page boundaries. The pages to the left and right of the object > > > page are "guard pages", whose attributes are changed to a protected > > > state, and cause page faults on any attempted access to them. Such page > > > faults are then intercepted by KFENCE, which handles the fault > > > gracefully by reporting a memory access error. > > > > To help understand the magic of KFENCE, a simple diagram looks needed to > > illustrate the relations between obj and guard pages, something like the > > below asiic chart. > > > > |-----------------|-----------------------------------|------------------| > > | left guard page | the page containing KFENCE object | right guard page | > > |-----------------|-----------------------------------|------------------| > > > > Would the one we have in Documentation be what you're after? Yes, that's great. > > https://lore.kernel.org/linux-arm-kernel/20200915132046.3332537-10-elver@xxxxxxxxxx/ > (at "The following figure illustrates the page layout::") > > Let us know if you'd like that copied into the commit message. Then the copy can help more readers. Thanks Hillf
