[PATCH 4.12 172/196] mlx5: Avoid that mlx5_ib_sg_to_klms() overflows the klms[] array

[Greg Kroah-Hartman]

4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>

commit 99975cd4fda52974a767aa44fe0b1a8f74950d9d upstream.

ib_map_mr_sg() can pass an SG-list to .map_mr_sg() that is larger
than what fits into a single MR. .map_mr_sg() must not attempt to
map more SG-list elements than what fits into a single MR.
Hence make sure that mlx5_ib_sg_to_klms() does not write outside
the MR klms[] array.

Fixes: b005d3164713 ("mlx5: Add arbitrary sg list support")
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Reviewed-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>
Cc: Sagi Grimberg <sagi@xxxxxxxxxxx>
Cc: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Cc: Israel Rukshin <israelr@xxxxxxxxxxxx>
Acked-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/hw/mlx5/mr.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -1779,7 +1779,7 @@ mlx5_ib_sg_to_klms(struct mlx5_ib_mr *mr
 	mr->ndescs = sg_nents;
 
 	for_each_sg(sgl, sg, sg_nents, i) {
-		if (unlikely(i > mr->max_descs))
+		if (unlikely(i >= mr->max_descs))
 			break;
 		klms[i].va = cpu_to_be64(sg_dma_address(sg) + sg_offset);
 		klms[i].bcount = cpu_to_be32(sg_dma_len(sg) - sg_offset);