Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751423AbdFAHP7 (ORCPT ); Thu, 1 Jun 2017 03:15:59 -0400 Received: from m12-12.163.com ([220.181.12.12]:39204 "EHLO m12-12.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751091AbdFAHP6 (ORCPT ); Thu, 1 Jun 2017 03:15:58 -0400 From: Jia-Ju Bai To: awalls@md.metrocast.net, mchehab@kernel.org Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Jia-Ju Bai Subject: [PATCH] cx18: Fix a sleep-in-atomic bug in snd_cx18_pcm_hw_free Date: Thu, 1 Jun 2017 15:17:51 +0800 Message-Id: <1496301472-2754-1-git-send-email-baijiaju1990@163.com> X-Mailer: git-send-email 1.7.9.5 X-CM-TRANSID: DMCowAB3fh4Yvy9ZnsRSHg--.24711S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7ZFy8Zw4Utr4kGr4kXr4kXrb_yoW8GrykpF WUtryFkrZ0qF1qqrn0yan5ZF1rCan3K34UKFW293srZF4fXa43JF1jyryUZFWYvr4kZanx JFy5Jr9xGFyDAFUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UHWl9UUUUU= X-Originating-IP: [166.111.70.19] X-CM-SenderInfo: xedlyx5dmximizq6il2tof0z/1tbiHhzpelSIVWUEFwAAsu Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1309 Lines: 39 The driver may sleep under a spin lock, and the function call path is: snd_cx18_pcm_hw_free (acquire the lock by spin_lock_irqsave) vfree --> may sleep To fix it, the "substream->runtime->dma_area" is passed to a temporary value, and mark it NULL when holding the lock. The memory is freed by vfree through the temporary value outside the lock holding. Signed-off-by: Jia-Ju Bai --- drivers/media/pci/cx18/cx18-alsa-pcm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/media/pci/cx18/cx18-alsa-pcm.c b/drivers/media/pci/cx18/cx18-alsa-pcm.c index 205a98d..8c51e4c 100644 --- a/drivers/media/pci/cx18/cx18-alsa-pcm.c +++ b/drivers/media/pci/cx18/cx18-alsa-pcm.c @@ -257,14 +257,17 @@ static int snd_cx18_pcm_hw_free(struct snd_pcm_substream *substream) { struct snd_cx18_card *cxsc = snd_pcm_substream_chip(substream); unsigned long flags; + unsigned char *dma_area = NULL; spin_lock_irqsave(&cxsc->slock, flags); if (substream->runtime->dma_area) { dprintk("freeing pcm capture region\n"); - vfree(substream->runtime->dma_area); + dma_area = substream->runtime->dma_area; substream->runtime->dma_area = NULL; } spin_unlock_irqrestore(&cxsc->slock, flags); + if (dma_area) + vfree(dma_area); return 0; } -- 1.7.9.5