[PATCH v1] dmaengine: idxd: Fix allowing write() from different address spaces

[Vinicius Costa Gomes]

Check if the process submitting the descriptor belongs to the same
address space as the one that opened the file, reject otherwise.

Fixes: 6827738dc684 ("dmaengine: idxd: add a write() method for applications to submit work")
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@xxxxxxxxx>
---
 drivers/dma/idxd/cdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index ff94ee892339..373c622fcddc 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -473,6 +473,9 @@ static ssize_t idxd_cdev_write(struct file *filp, const char __user *buf, size_t
 	ssize_t written = 0;
 	int i;
 
+	if (current->mm != ctx->mm)
+		return -EPERM;
+
 	for (i = 0; i < len/sizeof(struct dsa_hw_desc); i++) {
 		int rc = idxd_submit_user_descriptor(ctx, udesc + i);
 
-- 
2.49.0