From 041a4f44f4a6a8cca7378a3efe7b74959a34733f Mon Sep 17 00:00:00 2001 From: Vladimir Oltean Date: Thu, 5 May 2022 02:54:59 +0300 Subject: net: mscc: ocelot: mark traps with a bool instead of keeping them in a list Since the blamed commit, VCAP filters can appear on more than one list. If their action is "trap", they are chained on ocelot->traps via filter->trap_list. This is in addition to their normal placement on the VCAP block->rules list head. Therefore, when we free a VCAP filter, we must remove it from all lists it is a member of, including ocelot->traps. There are at least 2 bugs which are direct consequences of this design decision. First is the incorrect usage of list_empty(), meant to denote whether "filter" is chained into ocelot->traps via filter->trap_list. This does not do the correct thing, because list_empty() checks whether "head->next == head", but in our case, head->next == head->prev == NULL. So we dereference NULL pointers and die when we call list_del(). Second is the fact that not all places that should remove the filter from ocelot->traps do so. One example is ocelot_vcap_block_remove_filter(), which is where we have the main kfree(filter). By keeping freed filters in ocelot->traps we end up in a use-after-free in felix_update_trapping_destinations(). Attempting to fix all the buggy patterns is a whack-a-mole game which makes the driver unmaintainable. Actually this is what the previous patch version attempted to do: https://patchwork.kernel.org/project/netdevbpf/patch/20220503115728.834457-3-vladimir.oltean@nxp.com/ but it introduced another set of bugs, because there are other places in which create VCAP filters, not just ocelot_vcap_filter_create(): - ocelot_trap_add() - felix_tag_8021q_vlan_add_rx() - felix_tag_8021q_vlan_add_tx() Relying on the convention that all those code paths must call INIT_LIST_HEAD(&filter->trap_list) is not going to scale. So let's do what should have been done in the first place and keep a bool in struct ocelot_vcap_filter which denotes whether we are looking at a trapping rule or not. Iterating now happens over the main VCAP IS2 block->rules. The advantage is that we no longer risk having stale references to a freed filter, since it is only present in that list. Fixes: e42bd4ed09aa ("net: mscc: ocelot: keep traps in a list") Signed-off-by: Vladimir Oltean Signed-off-by: Jakub Kicinski (cherry picked from commit e1846cff2fe614d93a2f89461b5935678fd34bd9) Signed-off-by: Vladimir Oltean --- drivers/net/dsa/ocelot/felix.c | 7 ++++++- drivers/net/ethernet/mscc/ocelot.c | 11 +++-------- drivers/net/ethernet/mscc/ocelot_flower.c | 4 +--- 3 files changed, 10 insertions(+), 12 deletions(-) (limited to 'drivers') diff --git a/drivers/net/dsa/ocelot/felix.c b/drivers/net/dsa/ocelot/felix.c index 41d769012acc..e90d38902dbf 100644 --- a/drivers/net/dsa/ocelot/felix.c +++ b/drivers/net/dsa/ocelot/felix.c @@ -403,6 +403,7 @@ static int felix_update_trapping_destinations(struct dsa_switch *ds, { struct ocelot *ocelot = ds->priv; struct felix *felix = ocelot_to_felix(ocelot); + struct ocelot_vcap_block *block_vcap_is2; struct ocelot_vcap_filter *trap; enum ocelot_mask_mode mask_mode; unsigned long port_mask; @@ -422,9 +423,13 @@ static int felix_update_trapping_destinations(struct dsa_switch *ds, /* We are sure that "cpu" was found, otherwise * dsa_tree_setup_default_cpu() would have failed earlier. */ + block_vcap_is2 = &ocelot->block[VCAP_IS2]; /* Make sure all traps are set up for that destination */ - list_for_each_entry(trap, &ocelot->traps, trap_list) { + list_for_each_entry(trap, &block_vcap_is2->rules, list) { + if (!trap->is_trap) + continue; + /* Figure out the current trapping destination */ if (using_tag_8021q) { /* Redirect to the tag_8021q CPU port. If timestamps diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c index bdaf755cede4..930d0b692a42 100644 --- a/drivers/net/ethernet/mscc/ocelot.c +++ b/drivers/net/ethernet/mscc/ocelot.c @@ -1601,7 +1601,7 @@ int ocelot_trap_add(struct ocelot *ocelot, int port, trap->action.mask_mode = OCELOT_MASK_MODE_PERMIT_DENY; trap->action.port_mask = 0; trap->take_ts = take_ts; - list_add_tail(&trap->trap_list, &ocelot->traps); + trap->is_trap = true; new = true; } @@ -1613,10 +1613,8 @@ int ocelot_trap_add(struct ocelot *ocelot, int port, err = ocelot_vcap_filter_replace(ocelot, trap); if (err) { trap->ingress_port_mask &= ~BIT(port); - if (!trap->ingress_port_mask) { - list_del(&trap->trap_list); + if (!trap->ingress_port_mask) kfree(trap); - } return err; } @@ -1636,11 +1634,8 @@ int ocelot_trap_del(struct ocelot *ocelot, int port, unsigned long cookie) return 0; trap->ingress_port_mask &= ~BIT(port); - if (!trap->ingress_port_mask) { - list_del(&trap->trap_list); - + if (!trap->ingress_port_mask) return ocelot_vcap_filter_del(ocelot, trap); - } return ocelot_vcap_filter_replace(ocelot, trap); } diff --git a/drivers/net/ethernet/mscc/ocelot_flower.c b/drivers/net/ethernet/mscc/ocelot_flower.c index fb238a168e7b..7c0897e779dc 100644 --- a/drivers/net/ethernet/mscc/ocelot_flower.c +++ b/drivers/net/ethernet/mscc/ocelot_flower.c @@ -312,7 +312,7 @@ static int ocelot_flower_parse_action(struct ocelot *ocelot, int port, filter->action.cpu_copy_ena = true; filter->action.cpu_qu_num = 0; filter->type = OCELOT_VCAP_FILTER_OFFLOAD; - list_add_tail(&filter->trap_list, &ocelot->traps); + filter->is_trap = true; break; case FLOW_ACTION_POLICE: if (filter->block_id == PSFP_BLOCK_ID) { @@ -895,8 +895,6 @@ int ocelot_cls_flower_replace(struct ocelot *ocelot, int port, ret = ocelot_flower_parse(ocelot, port, ingress, f, filter); if (ret) { - if (!list_empty(&filter->trap_list)) - list_del(&filter->trap_list); kfree(filter); return ret; } -- cgit v1.2.3