linux-kernel - Re: [PATCH] drivers core: Free dma_range

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Message-ID: <CANCKTBtMcDQkAAyTY_k3h6Mh8MxQkKiav1=wpyODDChpDwzFug@mail.gmail.com>
Date:   Mon, 4 Jan 2021 10:55:58 -0500
From:   Jim Quinlan <jim2101024@...il.com>
To:     Jim Quinlan <james.quinlan@...adcom.com>, Meng.Li@...driver.com,
        open list <linux-kernel@...r.kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>, rafael@...nel.org,
        Kexin.Hao@...driver.com, Jim Quinlan <jim2101024@...il.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH] drivers core: Free dma_range_map when driver probe failed

> Subject: [PATCH] drivers core: Free dma_range_map when driver probe failed
>
> There will be memory leak if driver probe failed. Trace as below:
>   backtrace:
>     [<000000002415258f>] kmemleak_alloc+0x3c/0x50
>     [<00000000f447ebe4>] __kmalloc+0x208/0x530
>     [<0000000048bc7b3a>] of_dma_get_range+0xe4/0x1b0
>     [<0000000041e39065>] of_dma_configure_id+0x58/0x27c
>     [<000000006356866a>] platform_dma_configure+0x2c/0x40
>     ......
>     [<000000000afcf9b5>] ret_from_fork+0x10/0x3c
>
> This issue is introduced by commit e0d072782c73("dma-mapping:
> introduce DMA range map, supplanting dma_pfn_offset "). It doesn't
> free dma_range_map when driver probe failed and cause above
> memory leak. So, add code to free it in error path.
>
> Fixes: e0d072782c73("dma-mapping: introduce DMA range map, supplanting
> dma_pfn_offset ")
> Cc: stable@...r.kernel.org
> Signed-off-by: Meng Li <Meng.Li@...driver.com>
> ---
>  drivers/base/dd.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/base/dd.c b/drivers/base/dd.c
> index 148e81969e04..8e4871aa34bc 100644
> --- a/drivers/base/dd.c
> +++ b/drivers/base/dd.c
> @@ -612,6 +612,7 @@ static int really_probe(struct device *dev, struct
> device_driver *drv)
>         else if (drv->remove)
>                 drv->remove(dev);
>  probe_failed:
> +       kfree(dev->dma_range_map);
>         if (dev->bus)
>                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
>                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
> --
> 2.17.1
>
> --

Hi Meng,

Sorry for the delay -- I was on vacation.  I agree with you -- thanks.
However, note that in function  device_release()  in
drivers/base/core.c  there is this line:

kfree(dev->dma_range_map);

Won't this also be called  if all of the appropriate drivers' probes
fail for this device, effecting a double kfree?  Perhaps your patch
could also set "dev->dma_range_map" to NULL after calling kfree()?

Thanks much,
Jim Quinlan
Broadcom STB