Coverity complains of a possible dereference of a null return value.
5. returned_null: kzalloc returns NULL. [show details]
6. var_assigned: Assigning: si_data = NULL return value from kzalloc.
488 si_data = kzalloc(data_size, __GFP_DMA | GFP_KERNEL);
489 cbd.length = cpu_to_le16(data_size);
490
491 dma = dma_map_single(&priv->si->pdev->dev, si_data,
492 data_size, DMA_FROM_DEVICE);
While this kzalloc() is unlikely to fail, I did notice that the function
returned without unmapping si_data.
Fix this by refactoring the error paths and checking for kzalloc()
failure.
Fixes: 888ae5a3952ba ("net: enetc: add tc flower psfp offload driver")
Cc: Claudiu Manoil <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: [email protected]
Cc: [email protected] (open list)
Signed-off-by: Tim Gardner <[email protected]>
---
I am curious why you do not need to call dma_sync_single_for_device() before enetc_send_cmd()
in order to flush the contents of CPU cache to RAM. Is it because __GFP_DMA marks
that page as uncached ? Or is it because of the SOC this runs on ?
rtg
---
.../net/ethernet/freescale/enetc/enetc_qos.c | 22 +++++++++++--------
1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_qos.c b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
index 4577226d3c6a..a93c55b04287 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_qos.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
@@ -486,14 +486,16 @@ static int enetc_streamid_hw_set(struct enetc_ndev_priv *priv,
data_size = sizeof(struct streamid_data);
si_data = kzalloc(data_size, __GFP_DMA | GFP_KERNEL);
- cbd.length = cpu_to_le16(data_size);
+ if (!si_data)
+ return -ENOMEM;
+ cbd.length = cpu_to_le16(data_size);
dma = dma_map_single(&priv->si->pdev->dev, si_data,
data_size, DMA_FROM_DEVICE);
if (dma_mapping_error(&priv->si->pdev->dev, dma)) {
netdev_err(priv->si->ndev, "DMA mapping failed!\n");
- kfree(si_data);
- return -ENOMEM;
+ err = -ENOMEM;
+ goto out;
}
cbd.addr[0] = cpu_to_le32(lower_32_bits(dma));
@@ -512,12 +514,10 @@ static int enetc_streamid_hw_set(struct enetc_ndev_priv *priv,
err = enetc_send_cmd(priv->si, &cbd);
if (err)
- return -EINVAL;
+ goto out;
- if (!enable) {
- kfree(si_data);
- return 0;
- }
+ if (!enable)
+ goto out;
/* Enable the entry overwrite again incase space flushed by hardware */
memset(&cbd, 0, sizeof(cbd));
@@ -560,7 +560,11 @@ static int enetc_streamid_hw_set(struct enetc_ndev_priv *priv,
}
err = enetc_send_cmd(priv->si, &cbd);
- kfree(si_data);
+out:
+ if (!dma_mapping_error(&priv->si->pdev->dev, dma))
+ dma_unmap_single(&priv->si->pdev->dev, dma, data_size, DMA_FROM_DEVICE);
+
+ kfree(si_data);
return err;
}
--
2.33.1
> -----Original Message-----
> From: Tim Gardner <[email protected]>
> Sent: Tuesday, October 19, 2021 9:20 PM
[...]
> Subject: [PATCH][linux-next] net: enetc: unmap DMA in enetc_send_cmd()
>
> Coverity complains of a possible dereference of a null return value.
>
> 5. returned_null: kzalloc returns NULL. [show details]
> 6. var_assigned: Assigning: si_data = NULL return value from kzalloc.
> 488 si_data = kzalloc(data_size, __GFP_DMA | GFP_KERNEL);
> 489 cbd.length = cpu_to_le16(data_size);
> 490
> 491 dma = dma_map_single(&priv->si->pdev->dev, si_data,
> 492 data_size, DMA_FROM_DEVICE);
>
> While this kzalloc() is unlikely to fail, I did notice that the function
> returned without unmapping si_data.
>
> Fix this by refactoring the error paths and checking for kzalloc()
> failure.
>
> Fixes: 888ae5a3952ba ("net: enetc: add tc flower psfp offload driver")
> Cc: Claudiu Manoil <[email protected]>
> Cc: "David S. Miller" <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: [email protected]
> Cc: [email protected] (open list)
> Signed-off-by: Tim Gardner <[email protected]>
> ---
>
> I am curious why you do not need to call dma_sync_single_for_device()
> before enetc_send_cmd()
> in order to flush the contents of CPU cache to RAM. Is it because
> __GFP_DMA marks
> that page as uncached ? Or is it because of the SOC this runs on ?
>
Not sure how it works like this, but I think dma_alloc_coherent() should have
been used here instead of the kmalloc + dma_map scheme. I don't have the
means to test this particular code path however.
Acked-by: Claudiu Manoil <[email protected]>
On Tue, 19 Oct 2021 19:47:17 +0000 Claudiu Manoil wrote:
> > I am curious why you do not need to call dma_sync_single_for_device()
> > before enetc_send_cmd()
> > in order to flush the contents of CPU cache to RAM. Is it because
> > __GFP_DMA marks
> > that page as uncached ? Or is it because of the SOC this runs on ?
> >
>
> Not sure how it works like this, but I think dma_alloc_coherent() should have
> been used here instead of the kmalloc + dma_map scheme.
Using dma_alloc_coherent() seems simpler and more correct,
let's do that instead.