Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from David Miller:

 1) Use 32-bit index for tails calls in s390 bpf JIT, from Ilya
    Leoshkevich.

 2) Fix missed EPOLLOUT events in TCP, from Eric Dumazet. Same fix for
    SMC from Jason Baron.

 3) ipv6_mc_may_pull() should return 0 for malformed packets, not
    -EINVAL. From Stefano Brivio.

 4) Don't forget to unpin umem xdp pages in error path of
    xdp_umem_reg(). From Ivan Khoronzhuk.

 5) Fix sta object leak in mac80211, from Johannes Berg.

 6) Fix regression by not configuring PHYLINK on CPU port of bcm_sf2
    switches. From Florian Fainelli.

 7) Revert DMA sync removal from r8169 which was causing regressions on
    some MIPS Loongson platforms. From Heiner Kallweit.

 8) Use after free in flow dissector, from Jakub Sitnicki.

 9) Fix NULL derefs of net devices during ICMP processing across
    collect_md tunnels, from Hangbin Liu.

10) proto_register() memory leaks, from Zhang Lin.

11) Set NLM_F_MULTI flag in multipart netlink messages consistently,
    from John Fastabend.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (66 commits)
  r8152: Set memory to all 0xFFs on failed reg reads
  openvswitch: Fix conntrack cache with timeout
  ipv4: mpls: fix mpls_xmit for iptunnel
  nexthop: Fix nexthop_num_path for blackhole nexthops
  net: rds: add service level support in rds-info
  net: route dump netlink NLM_F_MULTI flag missing
  s390/qeth: reject oversized SNMP requests
  sock: fix potential memory leak in proto_register()
  MAINTAINERS: Add phylink keyword to SFF/SFP/SFP+ MODULE SUPPORT
  xfrm/xfrm_policy: fix dst dev null pointer dereference in collect_md mode
  ipv4/icmp: fix rt dst dev null pointer dereference
  openvswitch: Fix log message in ovs conntrack
  bpf: allow narrow loads of some sk_reuseport_md fields with offset > 0
  bpf: fix use after free in prog symbol exposure
  bpf: fix precision tracking in presence of bpf2bpf calls
  flow_dissector: Fix potential use-after-free on BPF_PROG_DETACH
  Revert "r8169: remove not needed call to dma_sync_single_for_device"
  ipv6: propagate ipv6_add_dev's error returns out of ipv6_find_idev
  net/ncsi: Fix the payload copying for the request coming from Netlink
  qed: Add cleanup in qed_slowpath_start()
  ...

2 files changed, 23 insertions, 16 deletions

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 5d141f16f6fa..272071e9112f 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1707,20 +1707,26 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)
 	if (err)
 		goto free_used_maps;
 
-	err = bpf_prog_new_fd(prog);
-	if (err < 0) {
-		/* failed to allocate fd.
-		 * bpf_prog_put() is needed because the above
-		 * bpf_prog_alloc_id() has published the prog
-		 * to the userspace and the userspace may
-		 * have refcnt-ed it through BPF_PROG_GET_FD_BY_ID.
-		 */
-		bpf_prog_put(prog);
-		return err;
-	}
-
+	/* Upon success of bpf_prog_alloc_id(), the BPF prog is
+	 * effectively publicly exposed. However, retrieving via
+	 * bpf_prog_get_fd_by_id() will take another reference,
+	 * therefore it cannot be gone underneath us.
+	 *
+	 * Only for the time /after/ successful bpf_prog_new_fd()
+	 * and before returning to userspace, we might just hold
+	 * one reference and any parallel close on that fd could
+	 * rip everything out. Hence, below notifications must
+	 * happen before bpf_prog_new_fd().
+	 *
+	 * Also, any failure handling from this point onwards must
+	 * be using bpf_prog_put() given the program is exposed.
+	 */
 	bpf_prog_kallsyms_add(prog);
 	perf_event_bpf_event(prog, PERF_BPF_EVENT_PROG_LOAD, 0);
+
+	err = bpf_prog_new_fd(prog);
+	if (err < 0)
+		bpf_prog_put(prog);
 	return err;
 
 free_used_maps:
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index c84d83f86141..b5c14c9d7b98 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -985,9 +985,6 @@ static void __mark_reg_unbounded(struct bpf_reg_state *reg)
 	reg->smax_value = S64_MAX;
 	reg->umin_value = 0;
 	reg->umax_value = U64_MAX;
-
-	/* constant backtracking is enabled for root only for now */
-	reg->precise = capable(CAP_SYS_ADMIN) ? false : true;
 }
 
 /* Mark a register as having a completely unknown (scalar) value. */
@@ -1014,7 +1011,11 @@ static void mark_reg_unknown(struct bpf_verifier_env *env,
 			__mark_reg_not_init(regs + regno);
 		return;
 	}
-	__mark_reg_unknown(regs + regno);
+	regs += regno;
+	__mark_reg_unknown(regs);
+	/* constant backtracking is enabled for root without bpf2bpf calls */
+	regs->precise = env->subprog_cnt > 1 || !env->allow_ptr_leaks ?
+			true : false;
 }
 
 static void __mark_reg_not_init(struct bpf_reg_state *reg)