Re: [PATCH v2] dma-buf: acquire name lock before read/write dma_buf.name

From: Guangming Cao <redacted>

Am 08.10.21 um 09:54 schrieb guangming.cao@mediatek.com:

quoted

From: Guangming Cao <redacted>

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 <redacted>

Reviewed-by: Christian König <christian.koenig@amd.com>

Going to push that upstream if nobody else objects.

Thanks,
Christian.

I'm sorry to disturb you, actually I need this patch to solve our issues.
Is there any question about it? seems it hasn't been merged into mainline.

Thanks,
Guangming.

quoted

---
  drivers/dma-buf/dma-buf.c | 3 +++
  1 file changed, 3 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 511fe0d217a0..a7f6fd13a635 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c

@@ -1372,6 +1372,8 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
  		if (ret)
  			goto error_unlock;
  
+
+		spin_lock(&buf_obj->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 +1381,7 @@ 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(&buf_obj->name_lock);
  
  		robj = buf_obj->resv;
  		fence = dma_resv_excl_fence(robj);

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