[PATCH AUTOSEL 4.9 3/6] ioat: ioat_alloc_ring() failure handling.

[Sasha Levin <sashal@kernel.org>]

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 49386ce04bf5..1389f0582e29 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -394,10 +394,11 @@ 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