From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Konstantin Khlebnikov , Catalin Marinas , Andrew Morton , Linus Torvalds , "Srivatsa S. Bhat" Subject: [PATCH 4.9 14/17] kmemleak: clear stale pointers from task stacks Date: Tue, 7 Aug 2018 20:51:50 +0200 Message-Id: <20180807172342.867453448@linuxfoundation.org> In-Reply-To: <20180807172342.071526922@linuxfoundation.org> References: <20180807172342.071526922@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Konstantin Khlebnikov 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 Acked-by: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [ Srivatsa: Backported to 4.9.y ] Signed-off-by: Srivatsa S. Bhat Signed-off-by: Greg Kroah-Hartman --- 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;