Am 08.10.21 um 08:29 schrieb guangming.cao@mediatek.com:

From: Guangming Cao Guangming.Cao@mediatek.com

Because dma-buf.name can be freed in func: "dma_buf_set_name", so, we need to acquire lock first before we read/write dma_buf.name to prevent Use After Free(UAF) issue.

Signed-off-by: Guangming Cao Guangming.Cao@mediatek.com

drivers/dma-buf/dma-buf.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 511fe0d217a0..aebb51b3ff52 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -80,7 +80,9 @@ static void dma_buf_release(struct dentry *dentry) dma_resv_fini(dmabuf->resv); module_put(dmabuf->owner);

• spin_lock(&dmabuf->name_lock); kfree(dmabuf->name);
• spin_unlock(&dmabuf->name_lock);

That here is certainly a NAK. This is the release function if somebody is changing the name on a released DMA-buf we have much bigger problems.

kfree(dmabuf); } @@ -1372,6 +1374,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) if (ret) goto error_unlock;

• spin_lock(&dmabuf->name_lock);
  

  seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n", buf_obj->size, buf_obj->file->f_flags, buf_obj->file->f_mode,

@@ -1379,6 +1383,7 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) buf_obj->exp_name, file_inode(buf_obj->file)->i_ino, buf_obj->name ?: "");

• spin_unlock(&dmabuf->name_lock);
  

Yeah, that part looks like a good idea to me as well.

Christian.

robj = buf_obj->resv; fence = dma_resv_excl_fence(robj);