linux-kernel - [PATCH] dmaengine: idxd: Fix passing freed memory in idxd_cdev

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Date:   Mon,  8 May 2023 23:07:16 -0700
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     error27@...il.com, kernel-janitors@...r.kernel.org,
        dan.carpenter@...aro.org,
        Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] dmaengine: idxd: Fix passing freed memory in idxd_cdev_open()

Smatch warns:
	drivers/dma/idxd/cdev.c:327:
		idxd_cdev_open() warn: 'sva' was already freed.

When idxd_wq_set_pasid() fails, the current code unbinds sva and then
goes to 'failed_set_pasid' where iommu_sva_unbind_device is called
again causing the above warning.
[ device_user_pasid_enabled(idxd) is still true when calling
failed_set_pasid ]

Fix this by removing additional unbind when idxd_wq_set_pasid() fails

Fixes: b022f59725f0 ("dmaengine: idxd: add idxd_copy_cr() to copy user completion record during page fault handling")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
---
This is purely based on static analysis. Only compile tested.
---
 drivers/dma/idxd/cdev.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
index ecbf67c2ad2b..d32deb9b4e3d 100644
--- a/drivers/dma/idxd/cdev.c
+++ b/drivers/dma/idxd/cdev.c
@@ -277,7 +277,6 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 		if (wq_dedicated(wq)) {
 			rc = idxd_wq_set_pasid(wq, pasid);
 			if (rc < 0) {
-				iommu_sva_unbind_device(sva);
 				dev_err(dev, "wq set pasid failed: %d\n", rc);
 				goto failed_set_pasid;
 			}
-- 
2.38.1