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authorAlexander Potapenko <glider@google.com>2022-09-15 17:04:04 +0200
committerAndrew Morton <akpm@linux-foundation.org>2022-10-03 14:03:23 -0700
commit42eaa27d9e7aafb4049fc3a5b02005a917013e65 (patch)
tree76a7eb109948f3bbf7417518f737b61c0169a7c1
parent74d899098854b4e56cf9dc9d0245d4d40f5efcd4 (diff)
security: kmsan: fix interoperability with auto-initialization
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. Link: https://lkml.kernel.org/r/20220915150417.722975-31-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Biggers <ebiggers@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Marco Elver <elver@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/page_alloc.c4
-rw-r--r--security/Kconfig.hardening4
2 files changed, 8 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 118462ae6800..c7e9451c69fc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -938,6 +938,10 @@ 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;
diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening
index bd2aabb2c60f..2739a6776454 100644
--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -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".