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

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Message-ID: <CAFCwf12jg7mS5wB05pfawOPrNC4rXXuSc=yJub5eWQBeHTTOQA@mail.gmail.com>
Date:   Thu, 1 Aug 2019 17:13:41 +0300
From:   Oded Gabbay <oded.gabbay@...il.com>
To:     Tomer Tayar <ttayar@...ana.ai>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] habanalabs: Avoid double free in error flow

On Thu, Aug 1, 2019 at 4:57 PM Tomer Tayar <ttayar@...ana.ai> 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 <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
>

This patch is:
Reviewed-by: Oded Gabbay <oded.gabbay@...il.com>
Applied to -fixed
Oded