| From 37f2a8dcabb2951e0ca5730956bc9db28394f42c Mon Sep 17 00:00:00 2001 |
| From: Liam Mark <lmark@codeaurora.org> |
| Date: Fri, 18 Jan 2019 10:37:44 -0800 |
| Subject: staging: android: ion: Support cpu access during dma_buf_detach |
| |
| [ Upstream commit 31eb79db420a3f94c4c45a8c0a05cd30e333f981 ] |
| |
| 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 <lmark@codeaurora.org> |
| Acked-by: Laura Abbott <labbott@redhat.com> |
| Acked-by: Andrew F. Davis <afd@ti.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| 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 99073325b0c00..45c7f829e3872 100644 |
| --- a/drivers/staging/android/ion/ion.c |
| +++ b/drivers/staging/android/ion/ion.c |
| @@ -237,10 +237,10 @@ 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); |
| } |
| -- |
| 2.19.1 |
| |
