5.0-stable review patch. If anyone has any objections, please let me know.
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From: Vlad Buslov vladbu@mellanox.com
[ Upstream commit ecb3dea400d3beaf611ce76ac7a51d4230492cf2 ]
When adding new filter to flower classifier, fl_change() inserts it to handle_idr before initializing filter extensions and assigning it a mask. Normally this ordering doesn't matter because all flower classifier ops callbacks assume rtnl lock protection. However, when filter has an action that doesn't have its kernel module loaded, rtnl lock is released before call to request_module(). During this time the filter can be accessed bu concurrent task before its initialization is completed, which can lead to a crash.
Example case of NULL pointer dereference in concurrent dump:
Task 1 Task 2
tc_new_tfilter() fl_change() idr_alloc_u32(fnew) fl_set_parms() tcf_exts_validate() tcf_action_init() tcf_action_init_1() rtnl_unlock() request_module() ... rtnl_lock() tc_dump_tfilter() tcf_chain_dump() fl_walk() idr_get_next_ul() tcf_node_dump() tcf_fill_node() fl_dump() mask = &f->mask->key; <- NULL ptr rtnl_lock()
Extension initialization and mask assignment don't depend on fnew->handle that is allocated by idr_alloc_u32(). Move idr allocation code after action creation and mask assignment in fl_change() to prevent concurrent access to not fully initialized filter when rtnl lock is released to load action module.
Fixes: 01683a146999 ("net: sched: refactor flower walk to iterate over idr") Signed-off-by: Vlad Buslov vladbu@mellanox.com Reviewed-by: Roi Dayan roid@mellanox.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sched/cls_flower.c | 43 ++++++++++++++++++++++--------------------- 1 file changed, 22 insertions(+), 21 deletions(-)
--- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -1327,46 +1327,46 @@ static int fl_change(struct net *net, st if (err < 0) goto errout;
- if (!handle) { - handle = 1; - err = idr_alloc_u32(&head->handle_idr, fnew, &handle, - INT_MAX, GFP_KERNEL); - } else if (!fold) { - /* user specifies a handle and it doesn't exist */ - err = idr_alloc_u32(&head->handle_idr, fnew, &handle, - handle, GFP_KERNEL); - } - if (err) - goto errout; - fnew->handle = handle; - if (tb[TCA_FLOWER_FLAGS]) { fnew->flags = nla_get_u32(tb[TCA_FLOWER_FLAGS]);
if (!tc_flags_valid(fnew->flags)) { err = -EINVAL; - goto errout_idr; + goto errout; } }
err = fl_set_parms(net, tp, fnew, mask, base, tb, tca[TCA_RATE], ovr, tp->chain->tmplt_priv, extack); if (err) - goto errout_idr; + goto errout;
err = fl_check_assign_mask(head, fnew, fold, mask); if (err) - goto errout_idr; + goto errout; + + if (!handle) { + handle = 1; + err = idr_alloc_u32(&head->handle_idr, fnew, &handle, + INT_MAX, GFP_KERNEL); + } else if (!fold) { + /* user specifies a handle and it doesn't exist */ + err = idr_alloc_u32(&head->handle_idr, fnew, &handle, + handle, GFP_KERNEL); + } + if (err) + goto errout_mask; + fnew->handle = handle;
if (!fold && __fl_lookup(fnew->mask, &fnew->mkey)) { err = -EEXIST; - goto errout_mask; + goto errout_idr; }
err = rhashtable_insert_fast(&fnew->mask->ht, &fnew->ht_node, fnew->mask->filter_ht_params); if (err) - goto errout_mask; + goto errout_idr;
if (!tc_skip_hw(fnew->flags)) { err = fl_hw_replace_filter(tp, fnew, extack); @@ -1405,12 +1405,13 @@ errout_mask_ht: rhashtable_remove_fast(&fnew->mask->ht, &fnew->ht_node, fnew->mask->filter_ht_params);
-errout_mask: - fl_mask_put(head, fnew->mask, false); - errout_idr: if (!fold) idr_remove(&head->handle_idr, fnew->handle); + +errout_mask: + fl_mask_put(head, fnew->mask, false); + errout: tcf_exts_destroy(&fnew->exts); kfree(fnew);