From patchwork Wed Jun 21 16:56:02 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Bader X-Patchwork-Id: 779027 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 3wt9pY1T67z9s4q; Thu, 22 Jun 2017 02:56:21 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1dNivS-0006x2-IV; Wed, 21 Jun 2017 16:56:18 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1dNivE-0006km-72 for kernel-team@lists.ubuntu.com; Wed, 21 Jun 2017 16:56:04 +0000 Received: from 1.general.smb.uk.vpn ([10.172.193.28] helo=canonical.com) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1dNivD-00086Y-Sd for kernel-team@lists.ubuntu.com; Wed, 21 Jun 2017 16:56:03 +0000 From: Stefan Bader To: kernel-team@lists.ubuntu.com Subject: [PATCH 2/2 T/X/Y/Z] ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT Date: Wed, 21 Jun 2017 18:56:02 +0200 Message-Id: <1498064162-21039-4-git-send-email-stefan.bader@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1498064162-21039-1-git-send-email-stefan.bader@canonical.com> References: <1498064162-21039-1-git-send-email-stefan.bader@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com From: Takashi Iwai snd_timer_user_tselect() reallocates the queue buffer dynamically, but it forgot to reset its indices. Since the read may happen concurrently with ioctl and snd_timer_user_tselect() allocates the buffer via kmalloc(), this may lead to the leak of uninitialized kernel-space data, as spotted via KMSAN: BUG: KMSAN: use of unitialized memory in snd_timer_user_read+0x6c4/0xa10 CPU: 0 PID: 1037 Comm: probe Not tainted 4.11.0-rc5+ #2739 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x143/0x1b0 lib/dump_stack.c:52 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007 kmsan_check_memory+0xc2/0x140 mm/kmsan/kmsan.c:1086 copy_to_user ./arch/x86/include/asm/uaccess.h:725 snd_timer_user_read+0x6c4/0xa10 sound/core/timer.c:2004 do_loop_readv_writev fs/read_write.c:716 __do_readv_writev+0x94c/0x1380 fs/read_write.c:864 do_readv_writev fs/read_write.c:894 vfs_readv fs/read_write.c:908 do_readv+0x52a/0x5d0 fs/read_write.c:934 SYSC_readv+0xb6/0xd0 fs/read_write.c:1021 SyS_readv+0x87/0xb0 fs/read_write.c:1018 This patch adds the missing reset of queue indices. Together with the previous fix for the ioctl/read race, we cover the whole problem. Reported-by: Alexander Potapenko Tested-by: Alexander Potapenko Cc: Signed-off-by: Takashi Iwai CVE-2017-1000380 (cherry-picked from commit ba3021b2c79b2fa9114f92790a99deb27a65b728) Signed-off-by: Stefan Bader --- sound/core/timer.c | 1 + 1 file changed, 1 insertion(+) diff --git a/sound/core/timer.c b/sound/core/timer.c index 1118bd8..cd67d1c 100644 --- a/sound/core/timer.c +++ b/sound/core/timer.c @@ -1618,6 +1618,7 @@ static int snd_timer_user_tselect(struct file *file, if (err < 0) goto __err; + tu->qhead = tu->qtail = tu->qused = 0; kfree(tu->queue); tu->queue = NULL; kfree(tu->tqueue);