On Thu, 17 Sep 2020 at 15:26, Hillf Danton <hdanton@xxxxxxxx> 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? 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. Thanks, -- Marco
