linux-stable.git/net/ipv6, branch v6.6.78

udp: gso: do not drop small packets when PMTU reduces

2025-02-17T08:40:12+00:00

[ Upstream commit 235174b2bed88501fda689c113c55737f99332d8 ]

Commit 4094871db1d6 ("udp: only do GSO if # of segs > 1") avoided GSO
for small packets. But the kernel currently dismisses GSO requests only
after checking MTU/PMTU on gso_size. This means any packets, regardless
of their payload sizes, could be dropped when PMTU becomes smaller than
requested gso_size. We encountered this issue in production and it
caused a reliability problem that new QUIC connection cannot be
established before PMTU cache expired, while non GSO sockets still
worked fine at the same time.

Ideally, do not check any GSO related constraints when payload size is
smaller than requested gso_size, and return EMSGSIZE instead of EINVAL
on MTU/PMTU check failure to be more specific on the error cause.

Fixes: 4094871db1d6 ("udp: only do GSO if # of segs > 1")
Signed-off-by: Yan Zhai 
Suggested-by: Willem de Bruijn 
Reviewed-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

inet: ipmr: fix data-races

2025-02-08T08:52:02+00:00

[ Upstream commit 3440fa34ad99d471f1085bc2f4dedeaebc310261 ]

Following fields of 'struct mr_mfc' can be updated
concurrently (no lock protection) from ip_mr_forward()
and ip6_mr_forward()

- bytes
- pkt
- wrong_if
- lastuse

They also can be read from other functions.

Convert bytes, pkt and wrong_if to atomic_long_t,
and use READ_ONCE()/WRITE_ONCE() for lastuse.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet 
Reviewed-by: David Ahern 
Link: https://patch.msgid.link/20250114221049.1190631-1-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

inetpeer: do not get a refcount in inet_getpeer()

2025-02-08T08:51:53+00:00

[ Upstream commit a853c609504e2d1d83e71285e3622fda1f1451d8 ]

All inet_getpeer() callers except ip4_frag_init() don't need
to acquire a permanent refcount on the inetpeer.

They can switch to full RCU protection.

Move the refcount_inc_not_zero() into ip4_frag_init(),
so that all the other callers no longer have to
perform a pair of expensive atomic operations on
a possibly contended cache line.

inet_putpeer() no longer needs to be exported.

After this patch, my DUT can receive 8,400,000 UDP packets
per second targeting closed ports, using 50% less cpu cycles
than before.

Also change two calls to l3mdev_master_ifindex() by
l3mdev_master_ifindex_rcu() (Ido ideas)

Fixes: 8c2bd38b95f7 ("icmp: change the order of rate limits")
Signed-off-by: Eric Dumazet 
Link: https://patch.msgid.link/20241215175629.1248773-5-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

inetpeer: remove create argument of inet_getpeer_v[46]()

2025-02-08T08:51:53+00:00

[ Upstream commit 661cd8fc8e9039819ca0c22e0add52b632240a9e ]

All callers of inet_getpeer_v4() and inet_getpeer_v6()
want to create an inetpeer.

Signed-off-by: Eric Dumazet 
Link: https://patch.msgid.link/20241215175629.1248773-2-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Stable-dep-of: a853c609504e ("inetpeer: do not get a refcount in inet_getpeer()")
Signed-off-by: Sasha Levin

ipv6: Fix soft lockups in fib6_select_path under high next hop churn

2025-02-01T17:37:52+00:00

commit d9ccb18f83ea2bb654289b6ecf014fd267cc988b upstream.

Soft lockups have been observed on a cluster of Linux-based edge routers
located in a highly dynamic environment. Using the `bird` service, these
routers continuously update BGP-advertised routes due to frequently
changing nexthop destinations, while also managing significant IPv6
traffic. The lockups occur during the traversal of the multipath
circular linked-list in the `fib6_select_path` function, particularly
while iterating through the siblings in the list. The issue typically
arises when the nodes of the linked list are unexpectedly deleted
concurrently on a different core—indicated by their 'next' and
'previous' elements pointing back to the node itself and their reference
count dropping to zero. This results in an infinite loop, leading to a
soft lockup that triggers a system panic via the watchdog timer.

Apply RCU primitives in the problematic code sections to resolve the
issue. Where necessary, update the references to fib6_siblings to
annotate or use the RCU APIs.

Include a test script that reproduces the issue. The script
periodically updates the routing table while generating a heavy load
of outgoing IPv6 traffic through multiple iperf3 clients. It
consistently induces infinite soft lockups within a couple of minutes.

Kernel log:

 0 [ffffbd13003e8d30] machine_kexec at ffffffff8ceaf3eb
 1 [ffffbd13003e8d90] __crash_kexec at ffffffff8d0120e3
 2 [ffffbd13003e8e58] panic at ffffffff8cef65d4
 3 [ffffbd13003e8ed8] watchdog_timer_fn at ffffffff8d05cb03
 4 [ffffbd13003e8f08] __hrtimer_run_queues at ffffffff8cfec62f
 5 [ffffbd13003e8f70] hrtimer_interrupt at ffffffff8cfed756
 6 [ffffbd13003e8fd0] __sysvec_apic_timer_interrupt at ffffffff8cea01af
 7 [ffffbd13003e8ff0] sysvec_apic_timer_interrupt at ffffffff8df1b83d
--  --
 8 [ffffbd13003d3708] asm_sysvec_apic_timer_interrupt at ffffffff8e000ecb
    [exception RIP: fib6_select_path+299]
    RIP: ffffffff8ddafe7b  RSP: ffffbd13003d37b8  RFLAGS: 00000287
    RAX: ffff975850b43600  RBX: ffff975850b40200  RCX: 0000000000000000
    RDX: 000000003fffffff  RSI: 0000000051d383e4  RDI: ffff975850b43618
    RBP: ffffbd13003d3800   R8: 0000000000000000   R9: ffff975850b40200
    R10: 0000000000000000  R11: 0000000000000000  R12: ffffbd13003d3830
    R13: ffff975850b436a8  R14: ffff975850b43600  R15: 0000000000000007
    ORIG_RAX: ffffffffffffffff  CS: 0010  SS: 0018
 9 [ffffbd13003d3808] ip6_pol_route at ffffffff8ddb030c
10 [ffffbd13003d3888] ip6_pol_route_input at ffffffff8ddb068c
11 [ffffbd13003d3898] fib6_rule_lookup at ffffffff8ddf02b5
12 [ffffbd13003d3928] ip6_route_input at ffffffff8ddb0f47
13 [ffffbd13003d3a18] ip6_rcv_finish_core.constprop.0 at ffffffff8dd950d0
14 [ffffbd13003d3a30] ip6_list_rcv_finish.constprop.0 at ffffffff8dd96274
15 [ffffbd13003d3a98] ip6_sublist_rcv at ffffffff8dd96474
16 [ffffbd13003d3af8] ipv6_list_rcv at ffffffff8dd96615
17 [ffffbd13003d3b60] __netif_receive_skb_list_core at ffffffff8dc16fec
18 [ffffbd13003d3be0] netif_receive_skb_list_internal at ffffffff8dc176b3
19 [ffffbd13003d3c50] napi_gro_receive at ffffffff8dc565b9
20 [ffffbd13003d3c80] ice_receive_skb at ffffffffc087e4f5 [ice]
21 [ffffbd13003d3c90] ice_clean_rx_irq at ffffffffc0881b80 [ice]
22 [ffffbd13003d3d20] ice_napi_poll at ffffffffc088232f [ice]
23 [ffffbd13003d3d80] __napi_poll at ffffffff8dc18000
24 [ffffbd13003d3db8] net_rx_action at ffffffff8dc18581
25 [ffffbd13003d3e40] __do_softirq at ffffffff8df352e9
26 [ffffbd13003d3eb0] run_ksoftirqd at ffffffff8ceffe47
27 [ffffbd13003d3ec0] smpboot_thread_fn at ffffffff8cf36a30
28 [ffffbd13003d3ee8] kthread at ffffffff8cf2b39f
29 [ffffbd13003d3f28] ret_from_fork at ffffffff8ce5fa64
30 [ffffbd13003d3f50] ret_from_fork_asm at ffffffff8ce03cbb

Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table")
Reported-by: Adrian Oliver 
Signed-off-by: Omid Ehtemam-Haghighi 
Cc: Shuah Khan 
Cc: Ido Schimmel 
Cc: Kuniyuki Iwashima 
Cc: Simon Horman 
Reviewed-by: David Ahern 
Link: https://patch.msgid.link/20241106010236.1239299-1-omid.ehtemamhaghighi@menlosecurity.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Rajani Kantha 
Signed-off-by: Greg Kroah-Hartman

net: fix data-races around sk->sk_forward_alloc

2025-01-23T16:21:19+00:00

commit 073d89808c065ac4c672c0a613a71b27a80691cb upstream.

Syzkaller reported this warning:
 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 16 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x1c5/0x1e0
 Modules linked in:
 CPU: 0 UID: 0 PID: 16 Comm: ksoftirqd/0 Not tainted 6.12.0-rc5 #26
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
 RIP: 0010:inet_sock_destruct+0x1c5/0x1e0
 Code: 24 12 4c 89 e2 5b 48 c7 c7 98 ec bb 82 41 5c e9 d1 18 17 ff 4c 89 e6 5b 48 c7 c7 d0 ec bb 82 41 5c e9 bf 18 17 ff 0f 0b eb 83 <0f> 0b eb 97 0f 0b eb 87 0f 0b e9 68 ff ff ff 66 66 2e 0f 1f 84 00
 RSP: 0018:ffffc9000008bd90 EFLAGS: 00010206
 RAX: 0000000000000300 RBX: ffff88810b172a90 RCX: 0000000000000007
 RDX: 0000000000000002 RSI: 0000000000000300 RDI: ffff88810b172a00
 RBP: ffff88810b172a00 R08: ffff888104273c00 R09: 0000000000100007
 R10: 0000000000020000 R11: 0000000000000006 R12: ffff88810b172a00
 R13: 0000000000000004 R14: 0000000000000000 R15: ffff888237c31f78
 FS:  0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007ffc63fecac8 CR3: 000000000342e000 CR4: 00000000000006f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  
  ? __warn+0x88/0x130
  ? inet_sock_destruct+0x1c5/0x1e0
  ? report_bug+0x18e/0x1a0
  ? handle_bug+0x53/0x90
  ? exc_invalid_op+0x18/0x70
  ? asm_exc_invalid_op+0x1a/0x20
  ? inet_sock_destruct+0x1c5/0x1e0
  __sk_destruct+0x2a/0x200
  rcu_do_batch+0x1aa/0x530
  ? rcu_do_batch+0x13b/0x530
  rcu_core+0x159/0x2f0
  handle_softirqs+0xd3/0x2b0
  ? __pfx_smpboot_thread_fn+0x10/0x10
  run_ksoftirqd+0x25/0x30
  smpboot_thread_fn+0xdd/0x1d0
  kthread+0xd3/0x100
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x34/0x50
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  
 ---[ end trace 0000000000000000 ]---

Its possible that two threads call tcp_v6_do_rcv()/sk_forward_alloc_add()
concurrently when sk->sk_state == TCP_LISTEN with sk->sk_lock unlocked,
which triggers a data-race around sk->sk_forward_alloc:
tcp_v6_rcv
    tcp_v6_do_rcv
        skb_clone_and_charge_r
            sk_rmem_schedule
                __sk_mem_schedule
                    sk_forward_alloc_add()
            skb_set_owner_r
                sk_mem_charge
                    sk_forward_alloc_add()
        __kfree_skb
            skb_release_all
                skb_release_head_state
                    sock_rfree
                        sk_mem_uncharge
                            sk_forward_alloc_add()
                            sk_mem_reclaim
                                // set local var reclaimable
                                __sk_mem_reclaim
                                    sk_forward_alloc_add()

In this syzkaller testcase, two threads call
tcp_v6_do_rcv() with skb->truesize=768, the sk_forward_alloc changes like
this:
 (cpu 1)             | (cpu 2)             | sk_forward_alloc
 ...                 | ...                 | 0
 __sk_mem_schedule() |                     | +4096 = 4096
                     | __sk_mem_schedule() | +4096 = 8192
 sk_mem_charge()     |                     | -768  = 7424
                     | sk_mem_charge()     | -768  = 6656
 ...                 |    ...              |
 sk_mem_uncharge()   |                     | +768  = 7424
 reclaimable=7424    |                     |
                     | sk_mem_uncharge()   | +768  = 8192
                     | reclaimable=8192    |
 __sk_mem_reclaim()  |                     | -4096 = 4096
                     | __sk_mem_reclaim()  | -8192 = -4096 != 0

The skb_clone_and_charge_r() should not be called in tcp_v6_do_rcv() when
sk->sk_state is TCP_LISTEN, it happens later in tcp_v6_syn_recv_sock().
Fix the same issue in dccp_v6_do_rcv().

Suggested-by: Eric Dumazet 
Reviewed-by: Eric Dumazet 
Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Signed-off-by: Wang Liang 
Link: https://patch.msgid.link/20241107023405.889239-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Alva Lan 
Signed-off-by: Greg Kroah-Hartman

ila: serialize calls to nf_register_net_hooks()

2025-01-09T12:32:03+00:00

[ Upstream commit 260466b576bca0081a7d4acecc8e93687aa22d0e ]

syzbot found a race in ila_add_mapping() [1]

commit 031ae72825ce ("ila: call nf_unregister_net_hooks() sooner")
attempted to fix a similar issue.

Looking at the syzbot repro, we have concurrent ILA_CMD_ADD commands.

Add a mutex to make sure at most one thread is calling nf_register_net_hooks().

[1]
 BUG: KASAN: slab-use-after-free in rht_key_hashfn include/linux/rhashtable.h:159 [inline]
 BUG: KASAN: slab-use-after-free in __rhashtable_lookup.constprop.0+0x426/0x550 include/linux/rhashtable.h:604
Read of size 4 at addr ffff888028f40008 by task dhcpcd/5501

CPU: 1 UID: 0 PID: 5501 Comm: dhcpcd Not tainted 6.13.0-rc4-syzkaller-00054-gd6ef8b40d075 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 
  __dump_stack lib/dump_stack.c:94 [inline]
  dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
  print_address_description mm/kasan/report.c:378 [inline]
  print_report+0xc3/0x620 mm/kasan/report.c:489
  kasan_report+0xd9/0x110 mm/kasan/report.c:602
  rht_key_hashfn include/linux/rhashtable.h:159 [inline]
  __rhashtable_lookup.constprop.0+0x426/0x550 include/linux/rhashtable.h:604
  rhashtable_lookup include/linux/rhashtable.h:646 [inline]
  rhashtable_lookup_fast include/linux/rhashtable.h:672 [inline]
  ila_lookup_wildcards net/ipv6/ila/ila_xlat.c:127 [inline]
  ila_xlat_addr net/ipv6/ila/ila_xlat.c:652 [inline]
  ila_nf_input+0x1ee/0x620 net/ipv6/ila/ila_xlat.c:185
  nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
  nf_hook_slow+0xbb/0x200 net/netfilter/core.c:626
  nf_hook.constprop.0+0x42e/0x750 include/linux/netfilter.h:269
  NF_HOOK include/linux/netfilter.h:312 [inline]
  ipv6_rcv+0xa4/0x680 net/ipv6/ip6_input.c:309
  __netif_receive_skb_one_core+0x12e/0x1e0 net/core/dev.c:5672
  __netif_receive_skb+0x1d/0x160 net/core/dev.c:5785
  process_backlog+0x443/0x15f0 net/core/dev.c:6117
  __napi_poll.constprop.0+0xb7/0x550 net/core/dev.c:6883
  napi_poll net/core/dev.c:6952 [inline]
  net_rx_action+0xa94/0x1010 net/core/dev.c:7074
  handle_softirqs+0x213/0x8f0 kernel/softirq.c:561
  __do_softirq kernel/softirq.c:595 [inline]
  invoke_softirq kernel/softirq.c:435 [inline]
  __irq_exit_rcu+0x109/0x170 kernel/softirq.c:662
  irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
  sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1049

Fixes: 7f00feaf1076 ("ila: Add generic ILA translation facility")
Reported-by: syzbot+47e761d22ecf745f72b9@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/6772c9ae.050a0220.2f3838.04c7.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet 
Cc: Florian Westphal 
Cc: Tom Herbert 
Link: https://patch.msgid.link/20241230162849.2795486-1-edumazet@google.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net: inet6: do not leave a dangling sk pointer in inet6_create()

2024-12-14T19:00:04+00:00

[ Upstream commit 9df99c395d0f55fb444ef39f4d6f194ca437d884 ]

sock_init_data() attaches the allocated sk pointer to the provided sock
object. If inet6_create() fails later, the sk object is released, but the
sock object retains the dangling sk pointer, which may cause use-after-free
later.

Clear the sock sk pointer on error.

Signed-off-by: Ignat Korchagin 
Reviewed-by: Kuniyuki Iwashima 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20241014153808.51894-8-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

net/ipv6: release expired exception dst cached in socket

2024-12-14T18:59:35+00:00

[ Upstream commit 3301ab7d5aeb0fe270f73a3d4810c9d1b6a9f045 ]

Dst objects get leaked in ip6_negative_advice() when this function is
executed for an expired IPv6 route located in the exception table. There
are several conditions that must be fulfilled for the leak to occur:
* an ICMPv6 packet indicating a change of the MTU for the path is received,
  resulting in an exception dst being created
* a TCP connection that uses the exception dst for routing packets must
  start timing out so that TCP begins retransmissions
* after the exception dst expires, the FIB6 garbage collector must not run
  before TCP executes ip6_negative_advice() for the expired exception dst

When TCP executes ip6_negative_advice() for an exception dst that has
expired and if no other socket holds a reference to the exception dst, the
refcount of the exception dst is 2, which corresponds to the increment
made by dst_init() and the increment made by the TCP socket for which the
connection is timing out. The refcount made by the socket is never
released. The refcount of the dst is decremented in sk_dst_reset() but
that decrement is counteracted by a dst_hold() intentionally placed just
before the sk_dst_reset() in ip6_negative_advice(). After
ip6_negative_advice() has finished, there is no other object tied to the
dst. The socket lost its reference stored in sk_dst_cache and the dst is
no longer in the exception table. The exception dst becomes a leaked
object.

As a result of this dst leak, an unbalanced refcount is reported for the
loopback device of a net namespace being destroyed under kernels that do
not contain e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"):
unregister_netdevice: waiting for lo to become free. Usage count = 2

Fix the dst leak by removing the dst_hold() in ip6_negative_advice(). The
patch that introduced the dst_hold() in ip6_negative_advice() was
92f1655aa2b22 ("net: fix __dst_negative_advice() race"). But 92f1655aa2b22
merely refactored the code with regards to the dst refcount so the issue
was present even before 92f1655aa2b22. The bug was introduced in
54c1a859efd9f ("ipv6: Don't drop cache route entry unless timer actually
expired.") where the expired cached route is deleted and the sk_dst_cache
member of the socket is set to NULL by calling dst_negative_advice() but
the refcount belonging to the socket is left unbalanced.

The IPv4 version - ipv4_negative_advice() - is not affected by this bug.
When the TCP connection times out ipv4_negative_advice() merely resets the
sk_dst_cache of the socket while decrementing the refcount of the
exception dst.

Fixes: 92f1655aa2b22 ("net: fix __dst_negative_advice() race")
Fixes: 54c1a859efd9f ("ipv6: Don't drop cache route entry unless timer actually expired.")
Link: https://lore.kernel.org/netdev/20241113105611.GA6723@incl/T/#u
Signed-off-by: Jiri Wiesner 
Reviewed-by: Eric Dumazet 
Link: https://patch.msgid.link/20241128085950.GA4505@incl
Signed-off-by: Jakub Kicinski 
Signed-off-by: Sasha Levin

ipv6: introduce dst_rt6_info() helper

2024-12-14T18:59:35+00:00

[ Upstream commit e8dfd42c17faf183415323db1ef0c977be0d6489 ]

Instead of (struct rt6_info *)dst casts, we can use :

 #define dst_rt6_info(_ptr) \
         container_of_const(_ptr, struct rt6_info, dst)

Some places needed missing const qualifiers :

ip6_confirm_neigh(), ipv6_anycast_destination(),
ipv6_unicast_destination(), has_gateway()

v2: added missing parts (David Ahern)

Signed-off-by: Eric Dumazet 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller 
Stable-dep-of: 3301ab7d5aeb ("net/ipv6: release expired exception dst cached in socket")
Signed-off-by: Sasha Levin