iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

staging: android: ion: Support cpu access during dma_buf_detach

Browse Source 
[ 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>
This commit is contained in:
Liam Mark 2019-01-18 10:37:44 -08:00 committed by Greg Kroah-Hartman
parent 0baaa08d1e
commit a0fe1581a2
1 changed files with 1 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/staging/android/ion/ion.c
View File

@ -257,10 +257,10 @@ 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);
}