[PATCH v2] net: dsa: Remove VLA usage
From: Kees Cook <hidden>
Date: 2018-07-17 04:10:41
From: Salvatore Mesoraca <redacted> We avoid 2 VLAs by using a pre-allocated field in dsa_switch. We also try to avoid dynamic allocation whenever possible (when using fewer than bits-per-long ports, which is the common case). Link: http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com Link: http://lkml.kernel.org/r/20180505185145.GB32630@lunn.ch Signed-off-by: Salvatore Mesoraca <redacted> [kees: tweak commit subject and message slightly] Signed-off-by: Kees Cook <redacted> --- include/net/dsa.h | 3 +++ net/dsa/dsa2.c | 14 ++++++++++++++ net/dsa/switch.c | 22 ++++++++++------------ 3 files changed, 27 insertions(+), 12 deletions(-)
diff --git a/include/net/dsa.h b/include/net/dsa.h
index fdbd6082945d..461e8a7661b7 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h@@ -259,6 +259,9 @@ struct dsa_switch { /* Number of switch port queues */ unsigned int num_tx_queues; + unsigned long *bitmap; + unsigned long _bitmap; + /* Dynamically allocated ports, keep last */ size_t num_ports; struct dsa_port ports[];
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index dc5d9af3dc80..a1917025e155 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c@@ -775,6 +775,20 @@ struct dsa_switch *dsa_switch_alloc(struct device *dev, size_t n) if (!ds) return NULL; + /* We avoid allocating memory outside dsa_switch + * if it is not needed. + */ + if (n <= sizeof(ds->_bitmap) * 8) { + ds->bitmap = &ds->_bitmap; + } else { + ds->bitmap = devm_kcalloc(dev, + BITS_TO_LONGS(n), + sizeof(unsigned long), + GFP_KERNEL); + if (unlikely(!ds->bitmap)) + return NULL; + } + ds->dev = dev; ds->num_ports = n;
diff --git a/net/dsa/switch.c b/net/dsa/switch.c
index b93511726069..142b294d3446 100644
--- a/net/dsa/switch.c
+++ b/net/dsa/switch.c@@ -136,21 +136,20 @@ static int dsa_switch_mdb_add(struct dsa_switch *ds, { const struct switchdev_obj_port_mdb *mdb = info->mdb; struct switchdev_trans *trans = info->trans; - DECLARE_BITMAP(group, ds->num_ports); int port; /* Build a mask of Multicast group members */ - bitmap_zero(group, ds->num_ports); + bitmap_zero(ds->bitmap, ds->num_ports); if (ds->index == info->sw_index) - set_bit(info->port, group); + set_bit(info->port, ds->bitmap); for (port = 0; port < ds->num_ports; port++) if (dsa_is_dsa_port(ds, port)) - set_bit(port, group); + set_bit(port, ds->bitmap); if (switchdev_trans_ph_prepare(trans)) - return dsa_switch_mdb_prepare_bitmap(ds, mdb, group); + return dsa_switch_mdb_prepare_bitmap(ds, mdb, ds->bitmap); - dsa_switch_mdb_add_bitmap(ds, mdb, group); + dsa_switch_mdb_add_bitmap(ds, mdb, ds->bitmap); return 0; }
@@ -204,21 +203,20 @@ static int dsa_switch_vlan_add(struct dsa_switch *ds, { const struct switchdev_obj_port_vlan *vlan = info->vlan; struct switchdev_trans *trans = info->trans; - DECLARE_BITMAP(members, ds->num_ports); int port; /* Build a mask of VLAN members */ - bitmap_zero(members, ds->num_ports); + bitmap_zero(ds->bitmap, ds->num_ports); if (ds->index == info->sw_index) - set_bit(info->port, members); + set_bit(info->port, ds->bitmap); for (port = 0; port < ds->num_ports; port++) if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port)) - set_bit(port, members); + set_bit(port, ds->bitmap); if (switchdev_trans_ph_prepare(trans)) - return dsa_switch_vlan_prepare_bitmap(ds, vlan, members); + return dsa_switch_vlan_prepare_bitmap(ds, vlan, ds->bitmap); - dsa_switch_vlan_add_bitmap(ds, vlan, members); + dsa_switch_vlan_add_bitmap(ds, vlan, ds->bitmap); return 0; }
--
2.17.1
--
Kees Cook
Pixel Security