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[mm,v3,35/38] kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS

Message ID 90635a81c52723268a9c9ebc683243dd88e4a4eb.1639432170.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show
Series kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS | expand

Commit Message

andrey.konovalov@linux.dev Dec. 13, 2021, 9:55 p.m. UTC 
From: Andrey Konovalov <andreyknvl@google.com>

Allow enabling CONFIG_KASAN_VMALLOC with SW_TAGS and HW_TAGS KASAN
modes.

Also adjust CONFIG_KASAN_VMALLOC description:

- Mention HW_TAGS support.
- Remove unneeded internal details: they have no place in Kconfig
  description and are already explained in the documentation.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 lib/Kconfig.kasan | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)
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Patch

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 879757b6dd14..1f3e620188a2 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -178,17 +178,17 @@  config KASAN_TAGS_IDENTIFY
 	  memory consumption.
 
 config KASAN_VMALLOC
-	bool "Back mappings in vmalloc space with real shadow memory"
-	depends on KASAN_GENERIC && HAVE_ARCH_KASAN_VMALLOC
+	bool "Check accesses to vmalloc allocations"
+	depends on HAVE_ARCH_KASAN_VMALLOC
 	help
-	  By default, the shadow region for vmalloc space is the read-only
-	  zero page. This means that KASAN cannot detect errors involving
-	  vmalloc space.
-
-	  Enabling this option will hook in to vmap/vmalloc and back those
-	  mappings with real shadow memory allocated on demand. This allows
-	  for KASAN to detect more sorts of errors (and to support vmapped
-	  stacks), but at the cost of higher memory usage.
+	  This mode makes KASAN check accesses to vmalloc allocations for
+	  validity.
+
+	  With software KASAN modes, checking is done for all types of vmalloc
+	  allocations. Enabling this option leads to higher memory usage.
+
+	  With hardware tag-based KASAN, only VM_ALLOC mappings are checked.
+	  There is no additional memory usage.
 
 config KASAN_KUNIT_TEST
 	tristate "KUnit-compatible tests of KASAN bug detection capabilities" if !KUNIT_ALL_TESTS