kmsan: handle task creation and exiting

Tell KMSAN that a new task is created, so the tool creates a backing
metadata structure for that task.

Link: https://lkml.kernel.org/r/20220915150417.722975-17-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>

3 files changed, 29 insertions, 0 deletions

diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c
index 5330138fda5b..112dce135c7f 100644
--- a/mm/kmsan/core.c
+++ b/mm/kmsan/core.c
@@ -37,6 +37,16 @@ bool kmsan_enabled __read_mostly;
  */
 DEFINE_PER_CPU(struct kmsan_ctx, kmsan_percpu_ctx);
 
+void kmsan_internal_task_create(struct task_struct *task)
+{
+	struct kmsan_ctx *ctx = &task->kmsan_ctx;
+	struct thread_info *info = current_thread_info();
+
+	__memset(ctx, 0, sizeof(*ctx));
+	ctx->allow_reporting = true;
+	kmsan_internal_unpoison_memory(info, sizeof(*info), false);
+}
+
 void kmsan_internal_poison_memory(void *address, size_t size, gfp_t flags,
 				  unsigned int poison_flags)
 {
diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c
index 000703c563a4..6f3e64b0b61f 100644
--- a/mm/kmsan/hooks.c
+++ b/mm/kmsan/hooks.c
@@ -27,6 +27,23 @@
  * skipping effects of functions like memset() inside instrumented code.
  */
 
+void kmsan_task_create(struct task_struct *task)
+{
+	kmsan_enter_runtime();
+	kmsan_internal_task_create(task);
+	kmsan_leave_runtime();
+}
+
+void kmsan_task_exit(struct task_struct *task)
+{
+	struct kmsan_ctx *ctx = &task->kmsan_ctx;
+
+	if (!kmsan_enabled || kmsan_in_runtime())
+		return;
+
+	ctx->allow_reporting = false;
+}
+
 void kmsan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags)
 {
 	if (unlikely(object == NULL))
diff --git a/mm/kmsan/kmsan.h b/mm/kmsan/kmsan.h
index 97d48b45dba5..77ee068c04ae 100644
--- a/mm/kmsan/kmsan.h
+++ b/mm/kmsan/kmsan.h
@@ -180,6 +180,8 @@ void kmsan_internal_set_shadow_origin(void *address, size_t size, int b,
 				      u32 origin, bool checked);
 depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id);
 
+void kmsan_internal_task_create(struct task_struct *task);
+
 bool kmsan_metadata_is_contiguous(void *addr, size_t size);
 void kmsan_internal_check_memory(void *addr, size_t size, const void *user_addr,
 				 int reason);