linux-kernel - [PATCH] habanalabs: Avoid double free in error flow

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Message-ID: <20190801135721.13211-1-ttayar@habana.ai>
Date:   Thu, 1 Aug 2019 13:57:36 +0000
From:   Tomer Tayar <ttayar@...ana.ai>
To:     "oded.gabbay@...il.com" <oded.gabbay@...il.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH] habanalabs: Avoid double free in error flow

In case kernel context init fails during device initialization, both
hl_ctx_put() and kfree() are called, ending with a double free of the
kernel context.
Calling kfree() is needed only when a failure happens between the
allocation of the kernel context and its initialization, so move it to
there and remove it from the error flow.

Signed-off-by: Tomer Tayar <ttayar@...ana.ai>
---
 drivers/misc/habanalabs/device.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/habanalabs/device.c b/drivers/misc/habanalabs/device.c
index 0c4894dd9c02..7a8f9d0b71b5 100644
--- a/drivers/misc/habanalabs/device.c
+++ b/drivers/misc/habanalabs/device.c
@@ -970,7 +970,8 @@ int hl_device_init(struct hl_device *hdev, struct class *hclass)
 	rc = hl_ctx_init(hdev, hdev->kernel_ctx, true);
 	if (rc) {
 		dev_err(hdev->dev, "failed to initialize kernel context\n");
-		goto free_ctx;
+		kfree(hdev->kernel_ctx);
+		goto mmu_fini;
 	}
 
 	rc = hl_cb_pool_init(hdev);
@@ -1053,8 +1054,6 @@ int hl_device_init(struct hl_device *hdev, struct class *hclass)
 	if (hl_ctx_put(hdev->kernel_ctx) != 1)
 		dev_err(hdev->dev,
 			"kernel ctx is still alive on initialization failure\n");
-free_ctx:
-	kfree(hdev->kernel_ctx);
 mmu_fini:
 	hl_mmu_fini(hdev);
 eq_fini:
-- 
2.17.1