Re: [PATCH] mm: Fix potential memory leak in sys_swapon

[Darrick J. Wong]

On Wed, Sep 30, 2020 at 06:18:03AM -0400, Miaohe Lin wrote:
> If we failed to drain inode, we would forget to free the swap address space
> allocated by init_swap_address_space() above.
> 
> Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>

LGTM,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>

--D

> ---
>  mm/swapfile.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 2b0c5fc1b0e6..4522b458a814 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -3342,7 +3342,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
>  	error = inode_drain_writes(inode);
>  	if (error) {
>  		inode->i_flags &= ~S_SWAPFILE;
> -		goto bad_swap_unlock_inode;
> +		goto free_swap_address_space;
>  	}
>  
>  	mutex_lock(&swapon_mutex);
> @@ -3367,6 +3367,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
>  
>  	error = 0;
>  	goto out;
> +free_swap_address_space:
> +	exit_swap_address_space(p->type);
>  bad_swap_unlock_inode:
>  	inode_unlock(inode);
>  bad_swap:
> -- 
> 2.19.1
>