| Message ID | 20190925230416.20126-1-navid.emamdoost@gmail.com |
|---|---|
| State | Rejected |
| Delegated to: | David Miller |
| Headers | show |
| Series | net: qrtr: fix memory leak in qrtr_tun_read_iter | expand |
On Wed, Sep 25, 2019 at 06:04:13PM -0500, Navid Emamdoost wrote: > In qrtr_tun_read_iter we need an error handling path to appropriately > release skb in cases of error. Release _what_ skb? > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> > --- > net/qrtr/tun.c | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c > index e35869e81766..0f6e6d1d2901 100644 > --- a/net/qrtr/tun.c > +++ b/net/qrtr/tun.c > @@ -54,19 +54,24 @@ static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to) > int count; > > while (!(skb = skb_dequeue(&tun->queue))) { The body of the loop is entered only if the loop condition has evaluated true. In this case, it means that the value of !(skb = skb_dequeue(&tun->queue)) had been true, i.e. the value of skb = skb_dequeue(&tun->queue) has been NULL, i.e. that skb_dequeue() has returned NULL, which had been copied into skb. In other words, in the body of that loop we have skb equal to NULL. > - if (filp->f_flags & O_NONBLOCK) > - return -EAGAIN; > + if (filp->f_flags & O_NONBLOCK) { > + count = -EAGAIN; > + goto out; > + } > > /* Wait until we get data or the endpoint goes away */ > if (wait_event_interruptible(tun->readq, > - !skb_queue_empty(&tun->queue))) > - return -ERESTARTSYS; > + !skb_queue_empty(&tun->queue))) { > + count = -ERESTARTSYS; > + goto out; > + } > } The meaning of that loop is fairly clear, isn't it? Keep looking int tun->queue until an skb shows up there. If it's not immediately there, fail with -EAGAIN for non-blocking files and wait on tun->readq until some skb arrives.
On Thu, Sep 26, 2019 at 12:21:12AM +0100, Al Viro wrote: > On Wed, Sep 25, 2019 at 06:04:13PM -0500, Navid Emamdoost wrote: > > In qrtr_tun_read_iter we need an error handling path to appropriately > > release skb in cases of error. > > Release _what_ skb? It is not a leak clearly! My bad ... > > > Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> > > --- > > net/qrtr/tun.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c > > index e35869e81766..0f6e6d1d2901 100644 > > --- a/net/qrtr/tun.c > > +++ b/net/qrtr/tun.c > > @@ -54,19 +54,24 @@ static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to) > > int count; > > > > while (!(skb = skb_dequeue(&tun->queue))) { > > The body of the loop is entered only if the loop condition has > evaluated true. In this case, it means that the value of > !(skb = skb_dequeue(&tun->queue)) > had been true, i.e. the value of > skb = skb_dequeue(&tun->queue) > has been NULL, i.e. that skb_dequeue() has returned NULL, which had > been copied into skb. > > In other words, in the body of that loop we have skb equal to NULL. > > > - if (filp->f_flags & O_NONBLOCK) > > - return -EAGAIN; > > + if (filp->f_flags & O_NONBLOCK) { > > + count = -EAGAIN; > > + goto out; > > + } > > > > /* Wait until we get data or the endpoint goes away */ > > if (wait_event_interruptible(tun->readq, > > - !skb_queue_empty(&tun->queue))) > > - return -ERESTARTSYS; > > + !skb_queue_empty(&tun->queue))) { > > + count = -ERESTARTSYS; > > + goto out; > > + } > > } > > The meaning of that loop is fairly clear, isn't it? Keep looking int > tun->queue until an skb shows up there. If it's not immediately there, > fail with -EAGAIN for non-blocking files and wait on tun->readq until > some skb arrives. Thanks for the explainations. Navid.
diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c index e35869e81766..0f6e6d1d2901 100644 --- a/net/qrtr/tun.c +++ b/net/qrtr/tun.c @@ -54,19 +54,24 @@ static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to) int count; while (!(skb = skb_dequeue(&tun->queue))) { - if (filp->f_flags & O_NONBLOCK) - return -EAGAIN; + if (filp->f_flags & O_NONBLOCK) { + count = -EAGAIN; + goto out; + } /* Wait until we get data or the endpoint goes away */ if (wait_event_interruptible(tun->readq, - !skb_queue_empty(&tun->queue))) - return -ERESTARTSYS; + !skb_queue_empty(&tun->queue))) { + count = -ERESTARTSYS; + goto out; + } } count = min_t(size_t, iov_iter_count(to), skb->len); if (copy_to_iter(skb->data, count, to) != count) count = -EFAULT; +out: kfree_skb(skb); return count;
In qrtr_tun_read_iter we need an error handling path to appropriately release skb in cases of error. Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> --- net/qrtr/tun.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)