4.9-stable review patch. If anyone has any objections, please let me know.
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From: Konstantin Khlebnikov khlebnikov@yandex-team.ru
commit ca182551857cc2c1e6a2b7f1e72090a137a15008 upstream.
Kmemleak considers any pointers on task stacks as references. This patch clears newly allocated and reused vmap stacks.
Link: http://lkml.kernel.org/r/150728990124.744199.8403409836394318684.stgit@buzz Signed-off-by: Konstantin Khlebnikov khlebnikov@yandex-team.ru Acked-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org [ Srivatsa: Backported to 4.9.y ] Signed-off-by: Srivatsa S. Bhat srivatsa@csail.mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/thread_info.h | 2 +- kernel/fork.c | 4 ++++ 2 files changed, 5 insertions(+), 1 deletion(-)
--- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -59,7 +59,7 @@ extern long do_no_restart_syscall(struct
#ifdef __KERNEL__
-#ifdef CONFIG_DEBUG_STACK_USAGE +#if IS_ENABLED(CONFIG_DEBUG_STACK_USAGE) || IS_ENABLED(CONFIG_DEBUG_KMEMLEAK) # define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_NOTRACK | \ __GFP_ZERO) #else --- a/kernel/fork.c +++ b/kernel/fork.c @@ -184,6 +184,10 @@ static unsigned long *alloc_thread_stack continue; this_cpu_write(cached_stacks[i], NULL);
+#ifdef CONFIG_DEBUG_KMEMLEAK + /* Clear stale pointers from reused stack. */ + memset(s->addr, 0, THREAD_SIZE); +#endif tsk->stack_vm_area = s; local_irq_enable(); return s->addr;