@@ -936,6 +936,10 @@ void init_mem_debugging_and_hardening(void)
else
static_branch_disable(&init_on_free);
+ if (IS_ENABLED(CONFIG_KMSAN) &&
+ (_init_on_alloc_enabled_early || _init_on_free_enabled_early))
+ pr_info("mem auto-init: please make sure init_on_alloc and init_on_free are disabled when running KMSAN\n");
+
#ifdef CONFIG_DEBUG_PAGEALLOC
if (!debug_pagealloc_enabled())
return;
@@ -106,6 +106,7 @@ choice
config INIT_STACK_ALL_PATTERN
bool "pattern-init everything (strongest)"
depends on CC_HAS_AUTO_VAR_INIT_PATTERN
+ depends on !KMSAN
help
Initializes everything on the stack (including padding)
with a specific debug value. This is intended to eliminate
@@ -124,6 +125,7 @@ choice
config INIT_STACK_ALL_ZERO
bool "zero-init everything (strongest and safest)"
depends on CC_HAS_AUTO_VAR_INIT_ZERO
+ depends on !KMSAN
help
Initializes everything on the stack (including padding)
with a zero value. This is intended to eliminate all
@@ -218,6 +220,7 @@ config STACKLEAK_RUNTIME_DISABLE
config INIT_ON_ALLOC_DEFAULT_ON
bool "Enable heap memory zeroing on allocation by default"
+ depends on !KMSAN
help
This has the effect of setting "init_on_alloc=1" on the kernel
command line. This can be disabled with "init_on_alloc=0".
@@ -230,6 +233,7 @@ config INIT_ON_ALLOC_DEFAULT_ON
config INIT_ON_FREE_DEFAULT_ON
bool "Enable heap memory zeroing on free by default"
+ depends on !KMSAN
help
This has the effect of setting "init_on_free=1" on the kernel
command line. This can be disabled with "init_on_free=0".
Heap and stack initialization is great, but not when we are trying uses of uninitialized memory. When the kernel is built with KMSAN, having kernel memory initialization enabled may introduce false negatives. We disable CONFIG_INIT_STACK_ALL_PATTERN and CONFIG_INIT_STACK_ALL_ZERO under CONFIG_KMSAN, making it impossible to auto-initialize stack variables in KMSAN builds. We also disable CONFIG_INIT_ON_ALLOC_DEFAULT_ON and CONFIG_INIT_ON_FREE_DEFAULT_ON to prevent accidental use of heap auto-initialization. We however still let the users enable heap auto-initialization at boot-time (by setting init_on_alloc=1 or init_on_free=1), in which case a warning is printed. Signed-off-by: Alexander Potapenko <glider@google.com> --- Link: https://linux-review.googlesource.com/id/I86608dd867018683a14ae1870f1928ad925f42e9 --- mm/page_alloc.c | 4 ++++ security/Kconfig.hardening | 4 ++++ 2 files changed, 8 insertions(+)