From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:52818 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965887AbeFNOLn (ORCPT ); Thu, 14 Jun 2018 10:11:43 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+cd8bcd40cb049efa2770@syzkaller.appspotmail.com, syzbot , Laura Abbott Subject: [PATCH 4.9 14/30] staging: android: ion: Switch to pr_warn_once in ion_buffer_destroy Date: Thu, 14 Jun 2018 16:04:55 +0200 Message-Id: <20180614132600.853948612@linuxfoundation.org> In-Reply-To: <20180614132600.255515394@linuxfoundation.org> References: <20180614132600.255515394@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Laura Abbott commit 45ad559a29629cb1c64ee636563c69b71524f077 upstream. Syzbot reported yet another warning with Ion: WARNING: CPU: 0 PID: 1467 at drivers/staging/android/ion/ion.c:122 ion_buffer_destroy+0xd4/0x190 drivers/staging/android/ion/ion.c:122 Kernel panic - not syncing: panic_on_warn set ... This is catching that a buffer was freed with an existing kernel mapping still present. This can be easily be triggered from userspace by calling DMA_BUF_SYNC_START without calling DMA_BUF_SYNC_END. Switch to a single pr_warn_once to indicate the error without being disruptive. Reported-by: syzbot+cd8bcd40cb049efa2770@syzkaller.appspotmail.com Reported-by: syzbot Signed-off-by: Laura Abbott Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ion/ion.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -192,8 +192,11 @@ err2: void ion_buffer_destroy(struct ion_buffer *buffer) { - if (WARN_ON(buffer->kmap_cnt > 0)) + if (buffer->kmap_cnt > 0) { + pr_warn_once("%s: buffer still mapped in the kernel\n", + __func__); buffer->heap->ops->unmap_kernel(buffer->heap, buffer); + } buffer->heap->ops->free(buffer); vfree(buffer->pages); kfree(buffer);