| Message ID | 20220214024134.223939-1-haiyue.wang@intel.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v1] gve: fix zero size queue page list allocation | expand |
On Mon, 14 Feb 2022 10:41:29 +0800 Haiyue Wang wrote: > According to the two functions 'gve_num_tx/rx_qpls', only the queue with > GVE_GQI_QPL_FORMAT format has queue page list. > > The 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero sized > memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT. > > The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL > address, so the driver can run successfully. Also the code still checks > the queue page list number firstly, then accesses the allocated memory, > so zero number queue page list allocation will not lead to access fault. > > Use the queue page list number to detect no QPLs, it can avoid zero size > queue page list memory allocation. There's no bug here, strictly speaking, the driver will function correctly? In that case please repost without the Fixes tag and with [PATCH net-next] in the subject. > Fixes: a5886ef4f4bf ("gve: Introduce per netdev `enum gve_queue_format`") > Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> -----Original Message----- > From: Jakub Kicinski <kuba@kernel.org> > Sent: Tuesday, February 15, 2022 13:22 > To: Wang, Haiyue <haiyue.wang@intel.com> > Cc: netdev@vger.kernel.org; Jeroen de Borst <jeroendb@google.com>; Catherine Sullivan > <csully@google.com>; David Awogbemila <awogbemila@google.com>; David S. Miller <davem@davemloft.net>; > Willem de Bruijn <willemb@google.com>; Forrest, Bailey <bcf@google.com>; Tao Liu <xliutaox@google.com>; > Christophe JAILLET <christophe.jaillet@wanadoo.fr>; John Fraker <jfraker@google.com>; Yangchun Fu > <yangchun@google.com>; open list <linux-kernel@vger.kernel.org> > Subject: Re: [PATCH v1] gve: fix zero size queue page list allocation > > On Mon, 14 Feb 2022 10:41:29 +0800 Haiyue Wang wrote: > > According to the two functions 'gve_num_tx/rx_qpls', only the queue with > > GVE_GQI_QPL_FORMAT format has queue page list. > > > > The 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero sized > > memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT. > > > > The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL > > address, so the driver can run successfully. Also the code still checks > > the queue page list number firstly, then accesses the allocated memory, > > so zero number queue page list allocation will not lead to access fault. > > > > Use the queue page list number to detect no QPLs, it can avoid zero size > > queue page list memory allocation. > > There's no bug here, strictly speaking, the driver will function > correctly? In that case please repost without the Fixes tag and Code design bug, the 'queue_format == GVE_GQI_RDA_FORMAT' is not correct. But, yes, it works. So still need to remove the tag ? > with [PATCH net-next] in the subject. > > > Fixes: a5886ef4f4bf ("gve: Introduce per netdev `enum gve_queue_format`") > > Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
On Tue, 15 Feb 2022 05:25:49 +0000 Wang, Haiyue wrote: > > On Mon, 14 Feb 2022 10:41:29 +0800 Haiyue Wang wrote: > > > According to the two functions 'gve_num_tx/rx_qpls', only the queue with > > > GVE_GQI_QPL_FORMAT format has queue page list. > > > > > > The 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero sized > > > memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT. > > > > > > The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL > > > address, so the driver can run successfully. Also the code still checks > > > the queue page list number firstly, then accesses the allocated memory, > > > so zero number queue page list allocation will not lead to access fault. > > > > > > Use the queue page list number to detect no QPLs, it can avoid zero size > > > queue page list memory allocation. > > > > There's no bug here, strictly speaking, the driver will function > > correctly? In that case please repost without the Fixes tag and > > Code design bug, the 'queue_format == GVE_GQI_RDA_FORMAT' is not correct. But, > yes, it works. So still need to remove the tag ? A bug is something that users can notice. If there are conditions under which this may lead to user-visible mis-behavior then we should keep the tag and send the patch to stable as well. If there is no user-visible problem here, then the patch is just future-proofing / refactoring and we should not risk introducing real bugs by making people backport it (which is what adding a Fixes will do).
> -----Original Message----- > From: Jakub Kicinski <kuba@kernel.org> > Sent: Tuesday, February 15, 2022 13:31 > To: Wang, Haiyue <haiyue.wang@intel.com> > Cc: netdev@vger.kernel.org; Jeroen de Borst <jeroendb@google.com>; Catherine Sullivan > <csully@google.com>; David Awogbemila <awogbemila@google.com>; David S. Miller <davem@davemloft.net>; > Willem de Bruijn <willemb@google.com>; Forrest, Bailey <bcf@google.com>; Tao Liu <xliutaox@google.com>; > Christophe JAILLET <christophe.jaillet@wanadoo.fr>; John Fraker <jfraker@google.com>; Yangchun Fu > <yangchun@google.com>; open list <linux-kernel@vger.kernel.org> > Subject: Re: [PATCH v1] gve: fix zero size queue page list allocation > > On Tue, 15 Feb 2022 05:25:49 +0000 Wang, Haiyue wrote: > > > On Mon, 14 Feb 2022 10:41:29 +0800 Haiyue Wang wrote: > > > > According to the two functions 'gve_num_tx/rx_qpls', only the queue with > > > > GVE_GQI_QPL_FORMAT format has queue page list. > > > > > > > > The 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero sized > > > > memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT. > > > > > > > > The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL > > > > address, so the driver can run successfully. Also the code still checks > > > > the queue page list number firstly, then accesses the allocated memory, > > > > so zero number queue page list allocation will not lead to access fault. > > > > > > > > Use the queue page list number to detect no QPLs, it can avoid zero size > > > > queue page list memory allocation. > > > > > > There's no bug here, strictly speaking, the driver will function > > > correctly? In that case please repost without the Fixes tag and > > > > Code design bug, the 'queue_format == GVE_GQI_RDA_FORMAT' is not correct. But, > > yes, it works. So still need to remove the tag ? > > A bug is something that users can notice. If there are conditions under > which this may lead to user-visible mis-behavior then we should keep > the tag and send the patch to stable as well. > > If there is no user-visible problem here, then the patch is just > future-proofing / refactoring and we should not risk introducing real > bugs by making people backport it (which is what adding a Fixes will > do). OK. Will remove the tag in v2.
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c index 54e51c8221b8..6cafee55efc3 100644 --- a/drivers/net/ethernet/google/gve/gve_main.c +++ b/drivers/net/ethernet/google/gve/gve_main.c @@ -857,8 +857,7 @@ static int gve_alloc_qpls(struct gve_priv *priv) int i, j; int err; - /* Raw addressing means no QPLs */ - if (priv->queue_format == GVE_GQI_RDA_FORMAT) + if (num_qpls == 0) return 0; priv->qpls = kvcalloc(num_qpls, sizeof(*priv->qpls), GFP_KERNEL); @@ -901,8 +900,7 @@ static void gve_free_qpls(struct gve_priv *priv) int num_qpls = gve_num_tx_qpls(priv) + gve_num_rx_qpls(priv); int i; - /* Raw addressing means no QPLs */ - if (priv->queue_format == GVE_GQI_RDA_FORMAT) + if (num_qpls == 0) return; kvfree(priv->qpl_cfg.qpl_id_map);
According to the two functions 'gve_num_tx/rx_qpls', only the queue with GVE_GQI_QPL_FORMAT format has queue page list. The 'queue_format == GVE_GQI_RDA_FORMAT' may lead to request zero sized memory allocation, like if the queue format is GVE_DQO_RDA_FORMAT. The kernel memory subsystem will return ZERO_SIZE_PTR, which is not NULL address, so the driver can run successfully. Also the code still checks the queue page list number firstly, then accesses the allocated memory, so zero number queue page list allocation will not lead to access fault. Use the queue page list number to detect no QPLs, it can avoid zero size queue page list memory allocation. Fixes: a5886ef4f4bf ("gve: Introduce per netdev `enum gve_queue_format`") Signed-off-by: Haiyue Wang <haiyue.wang@intel.com> --- drivers/net/ethernet/google/gve/gve_main.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)