From 69301eaa7fdab984c55c227359905fd522dbfc9c Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Mon, 15 Sep 2014 16:43:43 -0700 Subject: [PATCH] net_sched: fix a null pointer dereference in tcindex_set_parms() This patch fixes the following crash: [ 42.199159] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 42.200027] IP: [] tcindex_set_parms+0x45c/0x526 [ 42.200027] PGD d2319067 PUD d4ffe067 PMD 0 [ 42.200027] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC [ 42.200027] CPU: 0 PID: 541 Comm: tc Not tainted 3.17.0-rc4+ #603 [ 42.200027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 42.200027] task: ffff8800d22d2670 ti: ffff8800ce790000 task.ti: ffff8800ce790000 [ 42.200027] RIP: 0010:[] [] tcindex_set_parms+0x45c/0x526 [ 42.200027] RSP: 0018:ffff8800ce793898 EFLAGS: 00010202 [ 42.200027] RAX: 0000000000000001 RBX: ffff8800d1786498 RCX: 0000000000000000 [ 42.200027] RDX: ffffffff82114ec8 RSI: ffffffff82114ec8 RDI: ffffffff82114ec8 [ 42.200027] RBP: ffff8800ce793958 R08: 00000000000080d0 R09: 0000000000000001 [ 42.200027] R10: ffff8800ce7939a0 R11: 0000000000000246 R12: ffff8800d017d238 [ 42.200027] R13: 0000000000000018 R14: ffff8800d017c6a0 R15: ffff8800d1786620 [ 42.200027] FS: 00007f4e24539740(0000) GS:ffff88011a600000(0000) knlGS:0000000000000000 [ 42.200027] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 42.200027] CR2: 0000000000000018 CR3: 00000000cff38000 CR4: 00000000000006f0 [ 42.200027] Stack: [ 42.200027] ffff8800ce0949f0 0000000000000000 0000000200000003 ffff880000000000 [ 42.200027] ffff8800ce7938b8 ffff8800ce7938b8 0000000600000007 0000000000000000 [ 42.200027] ffff8800ce7938d8 ffff8800ce7938d8 0000000600000007 ffff8800ce0949f0 [ 42.200027] Call Trace: [ 42.200027] [] tcindex_change+0xdb/0xee [ 42.200027] [] tc_ctl_tfilter+0x44d/0x63f [ 42.200027] [] rtnetlink_rcv_msg+0x181/0x194 [ 42.200027] [] ? rtnl_lock+0x17/0x19 [ 42.200027] [] ? __rtnl_unlock+0x17/0x17 [ 42.200027] [] netlink_rcv_skb+0x49/0x8b [ 43.462494] [] rtnetlink_rcv+0x23/0x2a [ 43.462494] [] netlink_unicast+0xc7/0x148 [ 43.462494] [] netlink_sendmsg+0x5cb/0x63d [ 43.462494] [] ? mark_lock+0x2e/0x224 [ 43.462494] [] __sock_sendmsg_nosec+0x25/0x27 [ 43.462494] [] sock_sendmsg+0x57/0x71 [ 43.462494] [] ? might_fault+0x57/0xa4 [ 43.462494] [] ? might_fault+0xa0/0xa4 [ 43.462494] [] ? might_fault+0x57/0xa4 [ 43.462494] [] ? verify_iovec+0x69/0xb7 [ 43.462494] [] ___sys_sendmsg+0x21d/0x2bb [ 43.462494] [] ? native_sched_clock+0x35/0x37 [ 43.462494] [] ? sched_clock_local+0x12/0x72 [ 43.462494] [] ? mark_lock+0x2e/0x224 [ 43.462494] [] ? sched_clock_cpu+0xa0/0xb9 [ 43.462494] [] ? __lock_acquire+0x5fe/0xde4 [ 43.462494] [] ? rcu_read_lock_held+0x36/0x38 [ 43.462494] [] ? __fcheck_files.isra.7+0x4b/0x57 [ 43.462494] [] ? __fget_light+0x30/0x54 [ 43.462494] [] __sys_sendmsg+0x42/0x60 [ 43.462494] [] SyS_sendmsg+0x12/0x1c [ 43.462494] [] system_call_fastpath+0x16/0x1b 'p->h' could be NULL while 'cp->h' is always update to date. Fixes: commit 331b72922c5f58d48fd ("net: sched: RCU cls_tcindex") Cc: John Fastabend Signed-off-by: Cong Wang Acked-By: John Fastabend Signed-off-by: David S. Miller --- net/sched/cls_tcindex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c index ee525426b3d4..5054fae33a48 100644 --- a/net/sched/cls_tcindex.c +++ b/net/sched/cls_tcindex.c @@ -381,7 +381,7 @@ tcindex_set_parms(struct net *net, struct tcf_proto *tp, unsigned long base, f->result = new_filter_result; f->next = NULL; - fp = p->h + (handle % p->hash); + fp = cp->h + (handle % cp->hash); for (nfp = rtnl_dereference(*fp); nfp; fp = &nfp->next, nfp = rtnl_dereference(*fp)) -- 2.20.1