2019-08-01 14:00:26

by Tomer Tayar

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 <[email protected]>
---
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

2019-08-01 14:16:39

by Oded Gabbay

Subject: Re: [PATCH] habanalabs: Avoid double free in error flow

On Thu, Aug 1, 2019 at 4:57 PM Tomer Tayar <[email protected]> wrote:
>
> 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 <[email protected]>
> ---
> 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
>

This patch is:
Reviewed-by: Oded Gabbay <[email protected]>
Applied to -fixed
Oded