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authorAlexander Potapenko <glider@google.com>2022-09-15 17:03:49 +0200
committerAndrew Morton <akpm@linux-foundation.org>2022-10-03 14:03:20 -0700
commit68ef169a1dd20df5cfa5a161b7304ad9fdd14c36 (patch)
treeec9bfeb4d8165da74636d9900a2cb4d157ec4e1b /mm
parentb073d7f8aee4ebf05d10e3380df377b73120cf16 (diff)
mm: kmsan: call KMSAN hooks from SLUB code
In order to report uninitialized memory coming from heap allocations KMSAN has to poison them unless they're created with __GFP_ZERO. It's handy that we need KMSAN hooks in the places where init_on_alloc/init_on_free initialization is performed. In addition, we apply __no_kmsan_checks to get_freepointer_safe() to suppress reports when accessing freelist pointers that reside in freed objects. Link: https://lkml.kernel.org/r/20220915150417.722975-16-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Reviewed-by: Marco Elver <elver@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: 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>
Diffstat (limited to 'mm')
-rw-r--r--mm/kmsan/hooks.c76
-rw-r--r--mm/slab.h1
-rw-r--r--mm/slub.c17
3 files changed, 94 insertions, 0 deletions
diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 040111bb9f6a..000703c563a4 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -27,6 +27,82 @@
* skipping effects of functions like memset() inside instrumented code.
*/
+void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
+{
+ if (unlikely(object == NULL))
+ return;
+ if (!kmsan_enabled || kmsan_in_runtime())
+ return;
+ /*
+ * There's a ctor or this is an RCU cache - do nothing. The memory
+ * status hasn't changed since last use.
+ */
+ if (s->ctor || (s->flags & SLAB_TYPESAFE_BY_RCU))
+ return;
+
+ kmsan_enter_runtime();
+ if (flags & __GFP_ZERO)
+ kmsan_internal_unpoison_memory(object, s->object_size,
+ KMSAN_POISON_CHECK);
+ else
+ kmsan_internal_poison_memory(object, s->object_size, flags,
+ KMSAN_POISON_CHECK);
+ kmsan_leave_runtime();
+}
+
+void kmsan_slab_free(struct kmem_cache *s, void *object)
+{
+ if (!kmsan_enabled || kmsan_in_runtime())
+ return;
+
+ /* RCU slabs could be legally used after free within the RCU period */
+ if (unlikely(s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)))
+ return;
+ /*
+ * If there's a constructor, freed memory must remain in the same state
+ * until the next allocation. We cannot save its state to detect
+ * use-after-free bugs, instead we just keep it unpoisoned.
+ */
+ if (s->ctor)
+ return;
+ kmsan_enter_runtime();
+ kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL,
+ KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
+ kmsan_leave_runtime();
+}
+
+void kmsan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
+{
+ if (unlikely(ptr == NULL))
+ return;
+ if (!kmsan_enabled || kmsan_in_runtime())
+ return;
+ kmsan_enter_runtime();
+ if (flags & __GFP_ZERO)
+ kmsan_internal_unpoison_memory((void *)ptr, size,
+ /*checked*/ true);
+ else
+ kmsan_internal_poison_memory((void *)ptr, size, flags,
+ KMSAN_POISON_CHECK);
+ kmsan_leave_runtime();
+}
+
+void kmsan_kfree_large(const void *ptr)
+{
+ struct page *page;
+
+ if (!kmsan_enabled || kmsan_in_runtime())
+ return;
+ kmsan_enter_runtime();
+ page = virt_to_head_page((void *)ptr);
+ KMSAN_WARN_ON(ptr != page_address(page));
+ kmsan_internal_poison_memory((void *)ptr,
+ PAGE_SIZE << compound_order(page),
+ GFP_KERNEL,
+ KMSAN_POISON_CHECK | KMSAN_POISON_FREE);
+ kmsan_leave_runtime();
+}
+
static unsigned long vmalloc_shadow(unsigned long addr)
{
return (unsigned long)kmsan_get_metadata((void *)addr,
diff --git a/mm/slab.h b/mm/slab.h
index 4ec82bec15ec..9d0afd2985df 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -729,6 +729,7 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s,
memset(p[i], 0, s->object_size);
kmemleak_alloc_recursive(p[i], s->object_size, 1,
s->flags, flags);
+ kmsan_slab_alloc(s, p[i], flags);
}
memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
diff --git a/mm/slub.c b/mm/slub.c
index 6953c3367bc2..ce8310e131b3 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -22,6 +22,7 @@
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kasan.h>
+#include <linux/kmsan.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
@@ -359,6 +360,17 @@ static void prefetch_freepointer(const struct kmem_cache *s, void *object)
prefetchw(object + s->offset);
}
+/*
+ * When running under KMSAN, get_freepointer_safe() may return an uninitialized
+ * pointer value in the case the current thread loses the race for the next
+ * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in
+ * slab_alloc_node() will fail, so the uninitialized value won't be used, but
+ * KMSAN will still check all arguments of cmpxchg because of imperfect
+ * handling of inline assembly.
+ * To work around this problem, we apply __no_kmsan_checks to ensure that
+ * get_freepointer_safe() returns initialized memory.
+ */
+__no_kmsan_checks
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
{
unsigned long freepointer_addr;
@@ -1709,6 +1721,7 @@ static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
ptr = kasan_kmalloc_large(ptr, size, flags);
/* As ptr might get tagged, call kmemleak hook after KASAN. */
kmemleak_alloc(ptr, size, 1, flags);
+ kmsan_kmalloc_large(ptr, size, flags);
return ptr;
}
@@ -1716,12 +1729,14 @@ static __always_inline void kfree_hook(void *x)
{
kmemleak_free(x);
kasan_kfree_large(x);
+ kmsan_kfree_large(x);
}
static __always_inline bool slab_free_hook(struct kmem_cache *s,
void *x, bool init)
{
kmemleak_free_recursive(x, s->flags);
+ kmsan_slab_free(s, x);
debug_check_no_locks_freed(x, s->object_size);
@@ -5941,6 +5956,7 @@ static char *create_unique_id(struct kmem_cache *s)
p += sprintf(p, "%07u", s->size);
BUG_ON(p > name + ID_STR_LENGTH - 1);
+ kmsan_unpoison_memory(name, p - name);
return name;
}
@@ -6042,6 +6058,7 @@ static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
al->name = name;
al->next = alias_list;
alias_list = al;
+ kmsan_unpoison_memory(al, sizeof(*al));
return 0;
}