Re: [PATCH] xen/blkback: fix memory leaks

From: Roger Pau MonnÃ
Date: Mon Aug 12 2019 - 04:56:26 EST


On Sun, Aug 11, 2019 at 12:23:22PM -0500, Wenwen Wang wrote:
> In read_per_ring_refs(), after 'req' and related memory regions are
> allocated, xen_blkif_map() is invoked to map the shared frame, irq, and
> etc. However, if this mapping process fails, no cleanup is performed,
> leading to memory leaks. To fix this issue, invoke the cleanup before
> returning the error.
>
> Signed-off-by: Wenwen Wang <wenwen@xxxxxxxxxx>

Thanks!

> ---
> drivers/block/xen-blkback/xenbus.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
> index 3ac6a5d..b90dbcd 100644
> --- a/drivers/block/xen-blkback/xenbus.c
> +++ b/drivers/block/xen-blkback/xenbus.c
> @@ -965,6 +965,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
> }
> }
>
> + err = -ENOMEM;
> for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
> req = kzalloc(sizeof(*req), GFP_KERNEL);
> if (!req)
> @@ -987,7 +988,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
> err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn);

You could also move the xen_blkif_map cal before the allocation loop,
since there's nothing in xen_blkif_map that uses the memory allocated
AFAICT, but I'm fine either way.

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Roger.