Hi Kishon,
On 2/9/21 11:00 AM, Kishon Vijay Abraham I wrote:
> bcdma_get_*() and udma_get_*() checks if bchan/rchan/tchan/rflow is
> already allocated by checking if it has a NON NULL value. For the
> error cases, bchan/rchan/tchan/rflow will have error value
> and bcdma_get_*() 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
> bchan/rchan/tchan/rflow.
I think this can happen when a channel request fails and we get a second
request coming and faces with the not cleanup up tchan/rchan/bchan/rflow
from the previous failure.
Interesting that I have not faced with this, but it is a valid oversight
from me.
> Reset the value of bchan/rchan/tchan/rflow to NULL if the allocation
> actually fails.
>
> Fixes: 017794739702 ("dmaengine: ti: k3-udma: Initial support for K3 BCDMA")
> Fixes: 25dcb5dd7b7c ("dmaengine: ti: New driver for K3 UDMA")
Will this patch apply at any of these?
25dcb5dd7b7c does not have BCDMA (bchan)
017794739702 does not contain PKTDMA (tflow)
> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
> ---
> drivers/dma/ti/k3-udma.c | 30 +++++++++++++++++++++++++-----
> 1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c
> index 298460438bb4..aa4ef583ff83 100644
> --- a/drivers/dma/ti/k3-udma.c
> +++ b/drivers/dma/ti/k3-udma.c
> @@ -1330,6 +1330,7 @@ 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",
> @@ -1347,8 +1348,11 @@ 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;
>
> @@ -1358,6 +1362,7 @@ 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",
> @@ -1372,8 +1377,11 @@ 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;
> @@ -1403,6 +1411,7 @@ 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",
> @@ -1417,8 +1426,13 @@ 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)
> @@ -1472,6 +1486,7 @@ 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);
> @@ -1485,6 +1500,11 @@ 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;
> }
>
--
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