[PATCH v3 0/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error

[PATCH v3 0/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error

[Kishon Vijay Abraham I]

NULL pointer de-reference error was observed when all the PCIe endpoint
functions (22 function in J721E) request a DMA channel. The issue was
specfically observed when using mem-to-mem copy.

Changes from v2:
1) Fix commit subject and commit log to mention bchan/rchan/tchan to NULL
   suggested by Peter.

Changes from v1:
1) Split the patch for BCDMA and PKTDMA separately
2) Fixed the return value of udma_get_rflow() to 0.
3) Removed the fixes tag as the patches does not directly apply to the
commits.

v1 => https://lore.kernel.org/r/20210209090036.30832-1-kishon@ti.com
v2 => https://lore.kernel.org/r/20211027055625.11150-1-kishon@ti.com

Kishon Vijay Abraham I (2):
  dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail
  dmaengine: ti: k3-udma: Set rchan/tchan to NULL if a channel request
    fail

 drivers/dma/ti/k3-udma.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

-- 
2.17.1

[PATCH v3 1/2] dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail

[Kishon Vijay Abraham I]

bcdma_get_*() checks if bchan is already allocated by checking if it
has a NON NULL value. For the error cases, bchan will have error value
and bcdma_get_*() considers this as already allocated (PASS) since the
error values are NON NULL. This results in NULL pointer dereference
error while de-referencing bchan.

Reset the value of bchan to NULL if a channel request fails.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/dma/ti/k3-udma.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index a35858610780..14ae28830871 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -1348,6 +1348,7 @@ static int bcdma_get_bchan(struct udma_chan *uc)
 {
 	struct udma_dev *ud = uc->ud;
 	enum udma_tp_level tpl;
+	int ret;
 
 	if (uc->bchan) {
 		dev_dbg(ud->dev, "chan%d: already have bchan%d allocated\n",
@@ -1365,8 +1366,11 @@ static int bcdma_get_bchan(struct udma_chan *uc)
 		tpl = ud->bchan_tpl.levels - 1;
 
 	uc->bchan = __udma_reserve_bchan(ud, tpl, -1);
-	if (IS_ERR(uc->bchan))
-		return PTR_ERR(uc->bchan);
+	if (IS_ERR(uc->bchan)) {
+		ret = PTR_ERR(uc->bchan);
+		uc->bchan = NULL;
+		return ret;
+	}
 
 	uc->tchan = uc->bchan;
 
-- 
2.17.1

[PATCH v3 2/2] dmaengine: ti: k3-udma: Set rchan/tchan to NULL if a channel request fail

[Kishon Vijay Abraham I]

udma_get_*() checks if rchan/tchan/rflow is already allocated by checking
if it has a NON NULL value. For the error cases, rchan/tchan/rflow will
have error value and udma_get_*() considers this as already allocated
(PASS) since the error values are NON NULL. This results in NULL pointer
dereference error while de-referencing rchan/tchan/rflow.

Reset the value of rchan/tchan/rflow to NULL if a channel request fails.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/dma/ti/k3-udma.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
index 14ae28830871..041d8e32d630 100644
--- a/drivers/dma/ti/k3-udma.c
+++ b/drivers/dma/ti/k3-udma.c
@@ -1380,6 +1380,7 @@ static int bcdma_get_bchan(struct udma_chan *uc)
 static int udma_get_tchan(struct udma_chan *uc)
 {
 	struct udma_dev *ud = uc->ud;
+	int ret;
 
 	if (uc->tchan) {
 		dev_dbg(ud->dev, "chan%d: already have tchan%d allocated\n",
@@ -1394,8 +1395,11 @@ static int udma_get_tchan(struct udma_chan *uc)
 	 */
 	uc->tchan = __udma_reserve_tchan(ud, uc->config.channel_tpl,
 					 uc->config.mapped_channel_id);
-	if (IS_ERR(uc->tchan))
-		return PTR_ERR(uc->tchan);
+	if (IS_ERR(uc->tchan)) {
+		ret = PTR_ERR(uc->tchan);
+		uc->tchan = NULL;
+		return ret;
+	}
 
 	if (ud->tflow_cnt) {
 		int tflow_id;
@@ -1425,6 +1429,7 @@ static int udma_get_tchan(struct udma_chan *uc)
 static int udma_get_rchan(struct udma_chan *uc)
 {
 	struct udma_dev *ud = uc->ud;
+	int ret;
 
 	if (uc->rchan) {
 		dev_dbg(ud->dev, "chan%d: already have rchan%d allocated\n",
@@ -1439,8 +1444,13 @@ static int udma_get_rchan(struct udma_chan *uc)
 	 */
 	uc->rchan = __udma_reserve_rchan(ud, uc->config.channel_tpl,
 					 uc->config.mapped_channel_id);
+	if (IS_ERR(uc->rchan)) {
+		ret = PTR_ERR(uc->rchan);
+		uc->rchan = NULL;
+		return ret;
+	}
 
-	return PTR_ERR_OR_ZERO(uc->rchan);
+	return 0;
 }
 
 static int udma_get_chan_pair(struct udma_chan *uc)
@@ -1494,6 +1504,7 @@ static int udma_get_chan_pair(struct udma_chan *uc)
 static int udma_get_rflow(struct udma_chan *uc, int flow_id)
 {
 	struct udma_dev *ud = uc->ud;
+	int ret;
 
 	if (!uc->rchan) {
 		dev_err(ud->dev, "chan%d: does not have rchan??\n", uc->id);
@@ -1507,8 +1518,13 @@ static int udma_get_rflow(struct udma_chan *uc, int flow_id)
 	}
 
 	uc->rflow = __udma_get_rflow(ud, flow_id);
+	if (IS_ERR(uc->rflow)) {
+		ret = PTR_ERR(uc->rflow);
+		uc->rflow = NULL;
+		return ret;
+	}
 
-	return PTR_ERR_OR_ZERO(uc->rflow);
+	return 0;
 }
 
 static void bcdma_put_bchan(struct udma_chan *uc)
-- 
2.17.1

Re: [PATCH v3 0/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error

[Péter Ujfalusi]

Hi Kishon,

On 29/10/2021 18:12, Kishon Vijay Abraham I wrote:
> NULL pointer de-reference error was observed when all the PCIe endpoint
> functions (22 function in J721E) request a DMA channel. The issue was
> specfically observed when using mem-to-mem copy.
> 
> Changes from v2:
> 1) Fix commit subject and commit log to mention bchan/rchan/tchan to NULL
>    suggested by Peter.

Looks good, however the second patch also fixes the rflow. It is
mentioned in the commit message itself.

I suppose the reason for a split is that the UDMA part
(rchan/tchan/rflow) could be backported as fix for older kernel since
the bchan came later with BCDMA/PKTDMA support?

Can you find a good Fixes tag for these?

> 
> Changes from v1:
> 1) Split the patch for BCDMA and PKTDMA separately
> 2) Fixed the return value of udma_get_rflow() to 0.
> 3) Removed the fixes tag as the patches does not directly apply to the
> commits.
> 
> v1 => https://lore.kernel.org/r/20210209090036.30832-1-kishon@ti.com
> v2 => https://lore.kernel.org/r/20211027055625.11150-1-kishon@ti.com
> 
> Kishon Vijay Abraham I (2):
>   dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail
>   dmaengine: ti: k3-udma: Set rchan/tchan to NULL if a channel request
>     fail

dmaengine: ti: k3-udma: Set r/tchan or rflow to NULL if request fail

would have bee a better subject line, if you feel you can send an update.

Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>


> 
>  drivers/dma/ti/k3-udma.c | 32 ++++++++++++++++++++++++++------
>  1 file changed, 26 insertions(+), 6 deletions(-)
> 

-- 
Péter

Re: [PATCH v3 0/2] dmaengine: ti: k3-udma: Fix NULL pointer dereference error

[Kishon Vijay Abraham I]

Hi Peter,

On 30/10/21 12:15 pm, Péter Ujfalusi wrote:
> Hi Kishon,
> 
> On 29/10/2021 18:12, Kishon Vijay Abraham I wrote:
>> NULL pointer de-reference error was observed when all the PCIe endpoint
>> functions (22 function in J721E) request a DMA channel. The issue was
>> specfically observed when using mem-to-mem copy.
>>
>> Changes from v2:
>> 1) Fix commit subject and commit log to mention bchan/rchan/tchan to NULL
>>    suggested by Peter.
> 
> Looks good, however the second patch also fixes the rflow. It is
> mentioned in the commit message itself.
> 
> I suppose the reason for a split is that the UDMA part
> (rchan/tchan/rflow) could be backported as fix for older kernel since
> the bchan came later with BCDMA/PKTDMA support?
> 
> Can you find a good Fixes tag for these?

I'll now add "Cc: <Stable@vger.kernel.org>" so that it gets merged to 5.14. It
doesn't apply cleanly to any of the other stable kernel.
> 
>>
>> Changes from v1:
>> 1) Split the patch for BCDMA and PKTDMA separately
>> 2) Fixed the return value of udma_get_rflow() to 0.
>> 3) Removed the fixes tag as the patches does not directly apply to the
>> commits.
>>
>> v1 => https://lore.kernel.org/r/20210209090036.30832-1-kishon@ti.com
>> v2 => https://lore.kernel.org/r/20211027055625.11150-1-kishon@ti.com
>>
>> Kishon Vijay Abraham I (2):
>>   dmaengine: ti: k3-udma: Set bchan to NULL if a channel request fail
>>   dmaengine: ti: k3-udma: Set rchan/tchan to NULL if a channel request
>>     fail
> 
> dmaengine: ti: k3-udma: Set r/tchan or rflow to NULL if request fail
> 
> would have bee a better subject line, if you feel you can send an update.
> 
> Acked-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>

Thank You! Will fix and resend.

Best Regards,
Kishon