[PATCH AUTOSEL 5.4 09/26] dmaengine: k3dma: Avoid null pointer traversal

[PATCH AUTOSEL 5.4 09/26] dmaengine: k3dma: Avoid null pointer traversal

[Sasha Levin]

From: John Stultz <john.stultz@linaro.org>

[ Upstream commit 2f42e05b942fe2fbfb9bbc6e34e1dd8c3ce4f3a4 ]

In some cases we seem to submit two transactions in a row, which
causes us to lose track of the first. If we then cancel the
request, we may still get an interrupt, which traverses a null
ds_run value.

So try to avoid starting a new transaction if the ds_run value
is set.

While this patch avoids the null pointer crash, I've had some
reports of the k3dma driver still getting confused, which
suggests the ds_run/ds_done value handling still isn't quite
right. However, I've not run into an issue recently with it
so I think this patch is worth pushing upstream to avoid the
crash.

Signed-off-by: John Stultz <john.stultz@linaro.org>
[add ss tag]
Link: https://lore.kernel.org/r/20191218190906.6641-1-john.stultz@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/k3dma.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/k3dma.c b/drivers/dma/k3dma.c
index 4b36c8810517..d05471653224 100644
--- a/drivers/dma/k3dma.c
+++ b/drivers/dma/k3dma.c
@@ -229,9 +229,11 @@ static irqreturn_t k3_dma_int_handler(int irq, void *dev_id)
 			c = p->vchan;
 			if (c && (tc1 & BIT(i))) {
 				spin_lock_irqsave(&c->vc.lock, flags);
-				vchan_cookie_complete(&p->ds_run->vd);
-				p->ds_done = p->ds_run;
-				p->ds_run = NULL;
+				if (p->ds_run != NULL) {
+					vchan_cookie_complete(&p->ds_run->vd);
+					p->ds_done = p->ds_run;
+					p->ds_run = NULL;
+				}
 				spin_unlock_irqrestore(&c->vc.lock, flags);
 			}
 			if (c && (tc2 & BIT(i))) {
@@ -271,6 +273,10 @@ static int k3_dma_start_txd(struct k3_dma_chan *c)
 	if (BIT(c->phy->idx) & k3_dma_get_chan_stat(d))
 		return -EAGAIN;
 
+	/* Avoid losing track of  ds_run if a transaction is in flight */
+	if (c->phy->ds_run)
+		return -EAGAIN;
+
 	if (vd) {
 		struct k3_dma_desc_sw *ds =
 			container_of(vd, struct k3_dma_desc_sw, vd);
-- 
2.20.1

[PATCH AUTOSEL 5.4 19/26] ioat: ioat_alloc_ring() failure handling.

[Sasha Levin]

From: "Alexander.Barabash@dell.com" <Alexander.Barabash@dell.com>

[ Upstream commit b0b5ce1010ffc50015eaec72b0028aaae3f526bb ]

If dma_alloc_coherent() returns NULL in ioat_alloc_ring(), ring
allocation must not proceed.

Until now, if the first call to dma_alloc_coherent() in
ioat_alloc_ring() returned NULL, the processing could proceed, failing
with NULL-pointer dereferencing further down the line.

Signed-off-by: Alexander Barabash <alexander.barabash@dell.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/75e9c0e84c3345d693c606c64f8b9ab5@x13pwhopdag1307.AMER.DELL.COM
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/ioat/dma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index 1a422a8b43cf..18c011e57592 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -377,10 +377,11 @@ ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
 
 		descs->virt = dma_alloc_coherent(to_dev(ioat_chan),
 						 SZ_2M, &descs->hw, flags);
-		if (!descs->virt && (i > 0)) {
+		if (!descs->virt) {
 			int idx;
 
 			for (idx = 0; idx < i; idx++) {
+				descs = &ioat_chan->descs[idx];
 				dma_free_coherent(to_dev(ioat_chan), SZ_2M,
 						  descs->virt, descs->hw);
 				descs->virt = NULL;
-- 
2.20.1