diff options
authorJiri Kosina <jkosina@suse.cz>2016-08-16 23:52:58 +0200
committerDavid S. Miller <davem@davemloft.net>2016-08-18 21:19:08 -0700
commit69012ae425d76ecacc573ecdbd2c360bd8c2b842 (patch)
parentMerge branch 'tipc-next' (diff)
net: sched: fix handling of singleton qdiscs with qdisc_hash
qdisc_match_from_root() is now iterating over per-netdevice qdisc hashtable instead of going through a linked-list of qdiscs (independently on the actual underlying netdev), which was the case before the switch to hashtable for qdiscs. For singleton qdiscs, there is no underlying netdev associated though, and therefore dumping a singleton qdisc will panic, as qdisc_dev(root) will always be NULL. BUG: unable to handle kernel NULL pointer dereference at 0000000000000410 IP: [<ffffffff8167efac>] qdisc_match_from_root+0x2c/0x70 PGD 1aceba067 PUD 1aceb7067 PMD 0 Oops: 0000 [#1] PREEMPT SMP [ ... ] task: ffff8801ec996e00 task.stack: ffff8801ec934000 RIP: 0010:[<ffffffff8167efac>] [<ffffffff8167efac>] qdisc_match_from_root+0x2c/0x70 RSP: 0018:ffff8801ec937ab0 EFLAGS: 00010203 RAX: 0000000000000408 RBX: ffff88025e612000 RCX: ffffffffffffffd8 RDX: 0000000000000000 RSI: 00000000ffff0000 RDI: ffffffff81cf8100 RBP: ffff8801ec937ab0 R08: 000000000001c160 R09: ffff8802668032c0 R10: ffffffff81cf8100 R11: 0000000000000030 R12: 00000000ffff0000 R13: ffff88025e612000 R14: ffffffff81cf3140 R15: 0000000000000000 FS: 00007f24b9af6740(0000) GS:ffff88026f280000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000410 CR3: 00000001aceec000 CR4: 00000000001406e0 Stack: ffff8801ec937ad0 ffffffff81681210 ffff88025dd51a00 00000000fffffff1 ffff8801ec937b88 ffffffff81681e4e ffffffff81c42bc0 ffff880262431500 ffffffff81cf3140 ffff88025dd51a10 ffff88025dd51a24 00000000ec937b38 Call Trace: [<ffffffff81681210>] qdisc_lookup+0x40/0x50 [<ffffffff81681e4e>] tc_modify_qdisc+0x21e/0x550 [<ffffffff8166ae25>] rtnetlink_rcv_msg+0x95/0x220 [<ffffffff81209602>] ? __kmalloc_track_caller+0x172/0x230 [<ffffffff8166ad90>] ? rtnl_newlink+0x870/0x870 [<ffffffff816897b7>] netlink_rcv_skb+0xa7/0xc0 [<ffffffff816657c8>] rtnetlink_rcv+0x28/0x30 [<ffffffff8168919b>] netlink_unicast+0x15b/0x210 [<ffffffff81689569>] netlink_sendmsg+0x319/0x390 [<ffffffff816379f8>] sock_sendmsg+0x38/0x50 [<ffffffff81638296>] ___sys_sendmsg+0x256/0x260 [<ffffffff811b1275>] ? __pagevec_lru_add_fn+0x135/0x280 [<ffffffff811b1a90>] ? pagevec_lru_move_fn+0xd0/0xf0 [<ffffffff811b1140>] ? trace_event_raw_event_mm_lru_insertion+0x180/0x180 [<ffffffff811b1b85>] ? __lru_cache_add+0x75/0xb0 [<ffffffff817708a6>] ? _raw_spin_unlock+0x16/0x40 [<ffffffff811d8dff>] ? handle_mm_fault+0x39f/0x1160 [<ffffffff81638b15>] __sys_sendmsg+0x45/0x80 [<ffffffff81638b62>] SyS_sendmsg+0x12/0x20 [<ffffffff810038e7>] do_syscall_64+0x57/0xb0 Fix this by special-casing singleton qdiscs (those that don't have underlying netdevice) and introduce immediate handling of those rather than trying to go over an underlying netdevice. We're in the same situation in tc_dump_qdisc_root() and tc_dump_tclass_root(). Ultimately, this will have to be slightly reworked so that we are actually able to show singleton qdiscs (noop) in the dump properly; but we're not currently doing that anyway, so no regression there, and better do this in a gradual manner. Fixes: 59cc1f61f ("net: sched: convert qdisc linked list to hashtable") Reported-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Daniel Borkmann <daniel@iogearbox.net> Reported-by: David Ahern <dsa@cumulusnetworks.com> Tested-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 10 insertions, 0 deletions
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 25aada7b095c..ff515d01951e 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -260,6 +260,9 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
struct Qdisc *q;
+ if (!qdisc_dev(root))
+ return (root->handle == handle ? root : NULL);
if (!(root->flags & TCQ_F_BUILTIN) &&
root->handle == handle)
return root;
@@ -1451,6 +1454,10 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
goto done;
+ if (!qdisc_dev(root))
+ goto out;
hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
if (q_idx < s_q_idx) {
@@ -1775,6 +1782,9 @@ static int tc_dump_tclass_root(struct Qdisc *root, struct sk_buff *skb,
if (tc_dump_tclass_qdisc(root, skb, tcm, cb, t_p, s_t) < 0)
return -1;
+ if (!qdisc_dev(root))
+ return 0;
hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
if (tc_dump_tclass_qdisc(q, skb, tcm, cb, t_p, s_t) < 0)
return -1;