4.9-stable review patch. If anyone has any objections, please let me know.
------------------ From: Konstantin Khlebnikov <khlebni...@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 <khlebni...@yandex-team.ru> Acked-by: Catalin Marinas <catalin.mari...@arm.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> [ Srivatsa: Backported to 4.9.y ] Signed-off-by: Srivatsa S. Bhat <sriva...@csail.mit.edu> Signed-off-by: Greg Kroah-Hartman <gre...@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;
