Re: [PATCH 2/2] aio: fix potential leak in aio_run_iocb().

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On Thu, 1 May 2014, Benjamin LaHaise wrote:

> Date: Thu, 1 May 2014 09:07:09 -0400
> From: Benjamin LaHaise <bcrl@xxxxxxxxx>
> To: torvalds@xxxxxxxxxxxxxxxxxxxx
> Cc: linux-aio@xxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx,
>     stable@xxxxxxxxxxxxxxx, Leon Yu <chianglungyu@xxxxxxxxx>
> Subject: [PATCH 2/2] aio: fix potential leak in aio_run_iocb().
> 
> iovec should be reclaimed whenever caller of rw_copy_check_uvector() returns,
> but it doesn't hold when failure happens right after aio_setup_vectored_rw().
> 
> Fix that in a such way to avoid hairy goto.

As I already replied to Leon,

this does not seem right.

> 
> Signed-off-by: Leon Yu <chianglungyu@xxxxxxxxx>
> Signed-off-by: Benjamin LaHaise <bcrl@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
>  fs/aio.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/aio.c b/fs/aio.c
> index 2adbb03..a0ed6c7 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1327,10 +1327,8 @@ rw_common:
>  						&iovec, compat)
>  			: aio_setup_single_vector(req, rw, buf, &nr_segs,
>  						  iovec);
> -		if (ret)
> -			return ret;
> -
> -		ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);

here ret could be possibly set to a positive number.

> +		if (!ret)
> +			ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
>  		if (ret < 0) {

but here we're checking for negative and bail out. However this
changes the way it worked before this patch and the iovec would not
be reclaimed anyway as you mentioned in the commit description.

Thanks!
-Lukas

>  			if (iovec != &inline_vec)
>  				kfree(iovec);
> 
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