[PATCH] drivers/md: fix potential memleak

[PATCH] drivers/md: fix potential memleak

[Bernard Zhao]

In function get_bitmap_from_slot, when md_bitmap_create failed,
md_bitmap_destroy must be called to do clean up.

Signed-off-by: Bernard Zhao <bernard@vivo.com>
---
 drivers/md/md-bitmap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index bfd6026d7809..a227bd0b9301 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1961,6 +1961,7 @@ struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
 	bitmap = md_bitmap_create(mddev, slot);
 	if (IS_ERR(bitmap)) {
 		rv = PTR_ERR(bitmap);
+		md_bitmap_destroy(mddev)
 		return ERR_PTR(rv);
 	}
 
-- 
2.33.1

Re: [PATCH] drivers/md: fix potential memleak

[Song Liu]

On Sun, Nov 14, 2021 at 7:18 PM Bernard Zhao <bernard@vivo.com> wrote:
>
> In function get_bitmap_from_slot, when md_bitmap_create failed,
> md_bitmap_destroy must be called to do clean up.

Could you please explain which variable(s) need clean up?

Thanks,
Song

>
> Signed-off-by: Bernard Zhao <bernard@vivo.com>
> ---
>  drivers/md/md-bitmap.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
> index bfd6026d7809..a227bd0b9301 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -1961,6 +1961,7 @@ struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
>         bitmap = md_bitmap_create(mddev, slot);
>         if (IS_ERR(bitmap)) {
>                 rv = PTR_ERR(bitmap);
> +               md_bitmap_destroy(mddev)
>                 return ERR_PTR(rv);
>         }
>
> --
> 2.33.1
>

答复: [PATCH] drivers/md: fix potential memleak

[赵军奎]

-----邮件原件-----
发件人: bernard@vivo.com <bernard@vivo.com> 代表 Song Liu
发送时间: 2021年11月17日 15:06
收件人: 赵军奎 <bernard@vivo.com>
抄送: linux-raid <linux-raid@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>
主题: Re: [PATCH] drivers/md: fix potential memleak

On Sun, Nov 14, 2021 at 7:18 PM Bernard Zhao <bernard@vivo.com> wrote:
>
> In function get_bitmap_from_slot, when md_bitmap_create failed, 
> md_bitmap_destroy must be called to do clean up.

>Could you please explain which variable(s) need clean up?

Hi Song:
The follow is the function md_bitmap_create`s annotation :
/*
 * initialize the bitmap structure
 * if this returns an error, bitmap_destroy must be called to do clean up
 * once mddev->bitmap is set
 */
struct bitmap *md_bitmap_create(struct mddev *mddev, int slot)

It is mentioned that bitmap_destroy needs to be called to do clean up.
Other functions which called md_bitmap_create in the same file also called md_bitmap_create to clean up(in the error branch), but this one didn`t.
I am not sure if there is some gap?
Thanks!
BR//Bernard

>Thanks,
>Song

>
> Signed-off-by: Bernard Zhao <bernard@vivo.com>
> ---
>  drivers/md/md-bitmap.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index 
> bfd6026d7809..a227bd0b9301 100644
> --- a/drivers/md/md-bitmap.c
> +++ b/drivers/md/md-bitmap.c
> @@ -1961,6 +1961,7 @@ struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
>         bitmap = md_bitmap_create(mddev, slot);
>         if (IS_ERR(bitmap)) {
>                 rv = PTR_ERR(bitmap);
> +               md_bitmap_destroy(mddev)
>                 return ERR_PTR(rv);
>         }
>
> --
> 2.33.1
>

Re: [PATCH] drivers/md: fix potential memleak

[kernel test robot]

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Hi Bernard,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on song-md/md-next]
[also build test ERROR on v5.16-rc1 next-20211117]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Bernard-Zhao/drivers-md-fix-potential-memleak/20211115-112133
base:   git://git.kernel.org/pub/scm/linux/kernel/git/song/md.git md-next
config: x86_64-rhel-8.3-func (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/0d67c5d17f8404c6975f34e0c0edccdaa9ab913d
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Bernard-Zhao/drivers-md-fix-potential-memleak/20211115-112133
        git checkout 0d67c5d17f8404c6975f34e0c0edccdaa9ab913d
        # save the attached .config to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iommu/ drivers/md/ drivers/misc/sgi-gru/ fs/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/md/md-bitmap.c: In function 'get_bitmap_from_slot':
>> drivers/md/md-bitmap.c:1964:27: error: expected ';' before 'return'
    1964 |   md_bitmap_destroy(mddev)
         |                           ^
         |                           ;
    1965 |   return ERR_PTR(rv);
         |   ~~~~~~                   


vim +1964 drivers/md/md-bitmap.c

  1954	
  1955	/* caller need to free returned bitmap with md_bitmap_free() */
  1956	struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot)
  1957	{
  1958		int rv = 0;
  1959		struct bitmap *bitmap;
  1960	
  1961		bitmap = md_bitmap_create(mddev, slot);
  1962		if (IS_ERR(bitmap)) {
  1963			rv = PTR_ERR(bitmap);
> 1964			md_bitmap_destroy(mddev)
  1965			return ERR_PTR(rv);
  1966		}
  1967	
  1968		rv = md_bitmap_init_from_disk(bitmap, 0);
  1969		if (rv) {
  1970			md_bitmap_free(bitmap);
  1971			return ERR_PTR(rv);
  1972		}
  1973	
  1974		return bitmap;
  1975	}
  1976	EXPORT_SYMBOL(get_bitmap_from_slot);
  1977	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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Re: [PATCH] drivers/md: fix potential memleak

[Song Liu]

On Tue, Nov 16, 2021 at 9:57 PM 赵军奎 <bernard@vivo.com> wrote:
>
>
>
> -----邮件原件-----
> 发件人: bernard@vivo.com <bernard@vivo.com> 代表 Song Liu
> 发送时间: 2021年11月17日 15:06
> 收件人: 赵军奎 <bernard@vivo.com>
> 抄送: linux-raid <linux-raid@vger.kernel.org>; open list <linux-kernel@vger.kernel.org>
> 主题: Re: [PATCH] drivers/md: fix potential memleak
>
> On Sun, Nov 14, 2021 at 7:18 PM Bernard Zhao <bernard@vivo.com> wrote:
> >
> > In function get_bitmap_from_slot, when md_bitmap_create failed,
> > md_bitmap_destroy must be called to do clean up.
>
> >Could you please explain which variable(s) need clean up?
>
> Hi Song:
> The follow is the function md_bitmap_create`s annotation :
> /*
>  * initialize the bitmap structure
>  * if this returns an error, bitmap_destroy must be called to do clean up
>  * once mddev->bitmap is set
>  */
> struct bitmap *md_bitmap_create(struct mddev *mddev, int slot)
>
> It is mentioned that bitmap_destroy needs to be called to do clean up.
> Other functions which called md_bitmap_create in the same file also called md_bitmap_create to clean up(in the error branch), but this one didn`t.
> I am not sure if there is some gap?

I don't think we need to call md_bitmap_destroy in some of these cases.
Please read the code carefully can decide where these are needed based
on the logic of the code.

Thanks,
Song