archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-08 03:04:51 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

mm/kfence: disable KFENCE upon KASAN HW tags enablement

Browse source 
KFENCE does not currently support KASAN hardware tags.  As a result, the
two features are incompatible when enabled simultaneously.

Given that MTE provides deterministic protection and KFENCE is a
sampling-based debugging tool, prioritize the stronger hardware
protections.  Disable KFENCE initialization and free the pre-allocated
pool if KASAN hardware tags are detected to ensure the system maintains
the security guarantees provided by MTE.

Link: https://lkml.kernel.org/r/20260213095410.1862978-1-glider@google.com
Fixes: 0ce20dd840 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ernesto Martinez Garcia <ernesto.martinezgarcia@tugraz.at>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexander Potapenko 2026-02-13 10:54:10 +01:00 • committed by Andrew Morton
parent 6de23f81a5
commit 09833d99db
1 changed files with 15 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

15
mm/kfence/core.c
View file

@ -13,6 +13,7 @@
#include <linux/hash.h>
#include <linux/irq_work.h>
#include <linux/jhash.h>
#include <linux/kasan-enabled.h>
#include <linux/kcsan-checks.h>
#include <linux/kfence.h>
#include <linux/kmemleak.h>
@ -916,6 +917,20 @@ void __init kfence_alloc_pool_and_metadata(void)
if (!kfence_sample_interval)
return;
/*
* If KASAN hardware tags are enabled, disable KFENCE, because it
* does not support MTE yet.
*/
if (kasan_hw_tags_enabled()) {
pr_info("disabled as KASAN HW tags are enabled\n");
if (__kfence_pool) {
memblock_free(__kfence_pool, KFENCE_POOL_SIZE);
__kfence_pool = NULL;
}
kfence_sample_interval = 0;
return;
}
/*
* If the pool has already been initialized by arch, there is no need to
* re-allocate the memory pool.