2019-08-11 17:26:28

by Wenwen Wang

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

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 <[email protected]>
---
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);
if (err) {
xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
- return err;
+ goto fail;
}

return 0;
@@ -1007,8 +1008,7 @@ static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir)
}
kfree(req);
}
- return -ENOMEM;
-
+ return err;
}

static int connect_ring(struct backend_info *be)
--
2.7.4

2019-08-12 08:58:45

by Roger Pau Monne

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

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 <[email protected]>

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 Monn? <[email protected]>

Roger.

2019-08-12 12:44:35

by Boris Ostrovsky

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

On 8/11/19 1:23 PM, 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.


Reviewed-by: Boris Ostrovsky <[email protected]>

2019-08-12 14:20:04

by Jens Axboe

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

On 8/11/19 10:23 AM, 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.

Applied, thanks.

--
Jens Axboe