On Fri, Jun 12, 2026 at 04:44:22AM +0000, Dev Jain wrote: > Introduce a boot option to tag only at allocation time of the objects. This > reduces KASAN MTE overhead, the tradeoff being reduced ability of > catching bugs. > > Now, when a memory object will be freed, it will retain the random tag it > had at allocation time. This compromises on catching UAF bugs, till the > time the object is not reallocated, at which point it will have a new > random tag. > > Hence, not catching "use-after-free-before-reallocation" and not catching > "double-free" will be the compromise for reduced KASAN overhead. > > This is an RFC because we are not clear about the performance benefit. > > Android folks, please help with testing! > > --- > Applies on Linus master (9716c086c8e8). > > Dev Jain (2): > kasan: hw_tags: Use KASAN_PAGE_REDZONE for vmalloc redzoning > kasan: hw_tags: Add boot option to elide free time poisoning > > Documentation/dev-tools/kasan.rst | 4 +++ > mm/kasan/hw_tags.c | 45 +++++++++++++++++++++++++++++-- > mm/kasan/kasan.h | 23 +++++++++++++++- > 3 files changed, 69 insertions(+), 3 deletions(-) > > -- > 2.43.0
I tested out this series on one of our devices that has MTE support, and didn't see any functional issues. One thing I did notice though, and it's independent of this patch, is that the vmalloc_oob is failing, but that happens even if these patches aren't present. Thanks, Isaac
