From mboxrd@z Thu Jan 1 00:00:00 1970 From: Liam Mark Subject: [PATCH 1/4] staging: android: ion: Support cpu access during dma_buf_detach Date: Fri, 18 Jan 2019 10:37:44 -0800 Message-ID: <1547836667-13695-2-git-send-email-lmark@codeaurora.org> References: <1547836667-13695-1-git-send-email-lmark@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1547836667-13695-1-git-send-email-lmark@codeaurora.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: driverdev-devel-bounces@linuxdriverproject.org Sender: "devel" To: labbott@redhat.com, sumit.semwal@linaro.org Cc: devel@driverdev.osuosl.org, tkjos@android.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, afd@ti.com, linaro-mm-sig@lists.linaro.org, arve@android.com, john.stultz@linaro.org, joel@joelfernandes.org, maco@android.com, christian@brauner.io List-Id: dri-devel@lists.freedesktop.org Often userspace doesn't know when the kernel will be calling dma_buf_detach on the buffer. If userpace starts its CPU access at the same time as the sg list is being freed it could end up accessing the sg list after it has been freed. Thread A Thread B - DMA_BUF_IOCTL_SYNC IOCT - ion_dma_buf_begin_cpu_access - list_for_each_entry - ion_dma_buf_detatch - free_duped_table - dma_sync_sg_for_cpu Fix this by getting the ion_buffer lock before freeing the sg table memory. Fixes: 2a55e7b5e544 ("staging: android: ion: Call dma_map_sg for syncing and mapping") Signed-off-by: Liam Mark --- drivers/staging/android/ion/ion.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index a0802de8c3a1..6f5afab7c1a1 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -248,10 +248,10 @@ static void ion_dma_buf_detatch(struct dma_buf *dmabuf, struct ion_dma_buf_attachment *a = attachment->priv; struct ion_buffer *buffer = dmabuf->priv; - free_duped_table(a->table); mutex_lock(&buffer->lock); list_del(&a->list); mutex_unlock(&buffer->lock); + free_duped_table(a->table); kfree(a); } -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project