Re: [PATCH] PM: hibernate: Fix the exclusive get block device in test_resume mode

[Pengfei Xu <pengfei.xu@intel.com>]

On 2023-08-24 at 00:13:29 +0800, Chen Yu wrote:
> commit 5904de0d735b ("PM: hibernate: Do not get block device exclusively
> in test_resume mode") fixes a hibernation issue under test_resume mode.
> That commit is supposed to open the block device in non-exclusive mode
> when in test_resume. However the code did the opposite, which is against
> its description.
> 
> Fix this by really disabling exclusive mode under test_resume.
> 
> Reported-by: syzbot+38d04642cea49f3a3d2e@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000761f5f0603324129@google.com/
> Fixes: 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode")
> Signed-off-by: Chen Yu <yu.c.chen@intel.com>
> ---
>  kernel/power/swap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index f6ebcd00c410..c12b34dd529c 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -1518,7 +1518,7 @@ static void *swsusp_holder;
>  
>  int swsusp_check(bool snapshot_test)
>  {
> -	void *holder = snapshot_test ? &swsusp_holder : NULL;
> +	void *holder = snapshot_test ? NULL : &swsusp_holder;
>  	int error;
>  
>  	hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device, BLK_OPEN_READ,
> @@ -1573,7 +1573,7 @@ void swsusp_close(bool snapshot_test)
>  		return;
>  	}
>  
> -	blkdev_put(hib_resume_bdev, snapshot_test ? &swsusp_holder : NULL);
> +	blkdev_put(hib_resume_bdev, snapshot_test ? NULL : &swsusp_holder);
>  }

Reported-by: Pengfei Xu <pengfei.xu@intel.com>

This issue was reported in an Intel internal ticket by private syzkaller on
25/May/2023.
Thanks for consideration if possible.

Best Regards,
Thanks!

>  
>  /**
> -- 
> 2.25.1
>