Am 18.08.21 um 14:17 schrieb Sa, Nuno:
From: Christian König <christian.koenig@xxxxxxx>
Sent: Wednesday, August 18, 2021 2:10 PM
To: Sa, Nuno <Nuno.Sa@xxxxxxxxxx>; linaro-mm-sig@xxxxxxxxxxxxxxxx;
dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx
Cc: Rob Clark <rob@xxxxxx>; Sumit Semwal
<sumit.semwal@xxxxxxxxxx>
Subject: Re: [PATCH] dma-buf: return -EINVAL if dmabuf object is
NULL
[External]
To be honest I think the if(WARN_ON(!dmabuf)) return -EINVAL
handling
here is misleading in the first place.
Returning -EINVAL on a hard coding error is not good practice and
should
probably be removed from the DMA-buf subsystem in general.
Would you say to just return 0 then? I don't think that having the
dereference is also good..
No, just run into the dereference.
Passing NULL as the core object you are working on is a hard coding
error and not something we should bubble up as recoverable error.
I used -EINVAL to be coherent with the rest of the code.
I rather suggest to remove the check elsewhere as well.
Christian.
- Nuno Sá
Christian.
Am 18.08.21 um 13:58 schrieb Nuno Sá:
On top of warning about a NULL object, we also want to return with a
proper error code (as done in 'dma_buf_begin_cpu_access()').
Otherwise,
we will get a NULL pointer dereference.
Fixes: fc13020e086b ("dma-buf: add support for kernel cpu access")
Signed-off-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
---
drivers/dma-buf/dma-buf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-
buf.c
index 63d32261b63f..8ec7876dd523 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1231,7 +1231,8 @@ int dma_buf_end_cpu_access(struct
dma_buf *dmabuf,
{
int ret = 0;
- WARN_ON(!dmabuf);
+ if (WARN_ON(!dmabuf))
+ return -EINVAL;
might_lock(&dmabuf->resv->lock.base);
