linux-stable.git/net/core, branch v7.1.4

netpoll: fix a use-after-free on shutdown path

2026-07-18T14:55:27+00:00

commit 45f1458a85017a023f138b22ac5c76abd477db42 upstream.

There is a use-after-free error on netpoll, which is clearly detected by
KASAN.

      BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80
      Read of size 1 at addr ... by task kworker/9:1
      Workqueue: events queue_process
      Call Trace:
       skb_dequeue+0x1e/0xb0
       queue_process+0x2c/0x600
       process_scheduled_works+0x4b6/0x850
       worker_thread+0x414/0x5a0
      Allocated by task 242:
       __netpoll_setup+0x201/0x4a0
       netpoll_setup+0x249/0x550
       enabled_store+0x32f/0x380
      Freed by task 0:
       kfree+0x1b7/0x540
       rcu_core+0x3f8/0x7a0

The problem happens when there is a pending TX worker running in
parallel with the cleanup path.

This is what happens on netpoll shutdown path:

1) __netpoll_cleanup() is called
2) set dev->npinfo to NULL
3) call_rcu() with rcu_cleanup_netpoll_info()
  3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with
       cancel_delayed_work(), but doesn't wait for the worker to finish
4) and kfree(npinfo);

Because 3.1) doesn't really cancel the work, as the comment says "we
can't call cancel_delayed_work_sync here, as we are in softirq", the TX
worker can run after 4).

Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through
the work item via container_of().

Use disable_delayed_work_sync() to ensure the worker is completely
stopped and prevent any future re-arming attempts. Once npinfo is set
to NULL, senders will bail out and not queue new work. The disable flag
ensures any in-flight re-arming attempts also fail silently.

In the future, we can do the cleanup inline here without needing the
npinfo->rcu rcu_head, but that is net-next material.

Cc: stable@vger.kernel.org
Fixes: 38e6bc185d95 ("netpoll: make __netpoll_cleanup non-block")
Reviewed-by: Pavan Chebbi 
Signed-off-by: Breno Leitao 
Link: https://patch.msgid.link/20260625-netpoll_rcu_fix-v2-1-0748ffac1e98@debian.org
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink

2026-07-04T11:45:03+00:00

commit 8165f7ff57d9667d2bb477ef6af83ede7fed4ad7 upstream.

A tunnel changelink() operates on at most two netns, dev_net(dev) and
the tunnel link netns t->net. They differ once the device is created in
or moved to a netns other than the one the request runs in. The rtnl
changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a
caller privileged there but not in t->net can rewrite a tunnel that
lives in t->net.

Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in
net/core/rtnetlink.c. It requires CAP_NET_ADMIN in the link netns and is
skipped when the link netns is dev_net(dev), where the rtnl path already
checked it. The other patches in this series use the same helper.

Gate ipgre_changelink() and erspan_changelink() with it, at the top of
the op before any attribute is parsed, because the parsers update live
tunnel fields first. ipgre_netlink_parms() sets t->collect_md before
ip_tunnel_changelink() runs.

Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in
vti6_siocdevprivate().") added the same check on the ioctl path. This
adds it on RTM_NEWLINK.

Reported-by: Xiao Liang 
Closes: https://lore.kernel.org/netdev/CABAhCOSzP1vaThGV35_VnsRCb=87_CPjPVsTHbq905k8A+BuUg@mail.gmail.com/
Fixes: b57708add314 ("gre: add x-netns support")
Cc: stable@vger.kernel.org
Signed-off-by: Maoyi Xie 
Reviewed-by: Kuniyuki Iwashima 
Link: https://patch.msgid.link/20260612085941.3158249-2-maoyixie.tju@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net: skmsg: preserve sg.copy across SG transforms

2026-07-04T11:45:03+00:00

commit 406e8a651a7b854c41fecd5117bb282b3a6c2c6b upstream.

The sk_msg sg.copy bitmap is part of the scatterlist entry ownership
state. A set bit tells sk_msg_compute_data_pointers() not to expose the
entry through writable BPF ctx->data. This protects entries backed by
pages that are not private to the sk_msg, such as splice-backed file
page-cache pages.

Several sk_msg transform paths move, copy, split, or compact
msg->sg.data[] entries without moving the matching sg.copy bit. This can
make an externally backed entry arrive at a new slot with a clear copy
bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable
ctx->data and BPF stores can modify the original page cache.

Keep sg.copy synchronized with sg.data[] whenever entries are
transferred, shifted, split, or copied into a new sk_msg. Clear the bit
when an entry is replaced by a newly allocated private page or freed.
This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(),
sk_msg_xfer(), and tls_split_open_record(), including the partial tail
entry created during TLS open-record splitting.

Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")
Cc: stable@vger.kernel.org
Reported-by: Yiming Qian 
Reported-by: Keenan Dong 
Signed-off-by: Yiming Qian 
Link: https://patch.msgid.link/20260610062137.49075-1-yimingqian591@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net: guard timestamp cmsgs to real error queue skbs

2026-06-10T01:32:08+00:00

skb_is_err_queue() treats PACKET_OUTGOING as the sole marker for an skb
from sk_error_queue. That assumption is not true for AF_PACKET sockets:
outgoing packet taps are also delivered to packet sockets with
skb->pkt_type == PACKET_OUTGOING, but their skb->cb is owned by AF_PACKET
instead of struct sock_exterr_skb.

If such an skb is received with timestamping enabled, the generic
timestamp cmsg path can read AF_PACKET control-buffer state as
sock_exterr_skb::opt_stats. With SO_RXQ_OVFL enabled, the packet drop
counter overlaps opt_stats. An odd drop count makes the path emit
SCM_TIMESTAMPING_OPT_STATS with skb->len and skb->data. For non-linear
skbs this copies past the linear head and can trigger hardened usercopy or
disclose adjacent heap contents.

Keep skb_is_err_queue() local to net/socket.c, but make it verify that
the PACKET_OUTGOING marker is paired with the sock_rmem_free destructor
installed by sock_queue_err_skb(). AF_PACKET receive skbs use normal
receive ownership and no longer pass as error-queue skbs, while legitimate
sk_error_queue entries keep the PACKET_OUTGOING marker and sock_rmem_free
ownership.

Fixes: 8605330aac5a ("tcp: fix SCM_TIMESTAMPING_OPT_STATS for normal skbs")
Signed-off-by: Kyle Zeng 
Reviewed-by: Kuniyuki Iwashima 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/20260607021819.49698-1-kylebot@openai.com
Signed-off-by: Jakub Kicinski

netdev: fix double-free in netdev_nl_bind_rx_doit()

2026-06-09T00:40:20+00:00

Sashiko flags that genlmsg_reply() always consumes the skb.
The error path calls nlmsg_free(rsp) so we can't jump directly
to it. Let's not unbind, just propagate the error to the user.
This is the typical way of handling genlmsg_reply() failures.
They shouldn't happen unless user does something silly like
calling the kernel with an already-full rcvbuf.

Reported-by: Sashiko 
Fixes: 170aafe35cb9 ("netdev: support binding dma-buf to netdevice")
Reviewed-by: Bobby Eshleman 
Acked-by: Daniel Borkmann 
Reviewed-by: Nikolay Aleksandrov 
Signed-off-by: Jakub Kicinski

net: add pskb_may_pull() to skb_gro_receive_list()

2026-06-09T00:20:23+00:00

skb_gro_receive_list() calls skb_pull(skb, skb_gro_offset(skb)) without
first ensuring the data is in the linear area via pskb_may_pull(). When
the skb arrives via napi_gro_frags(), skb_headlen can be 0 (all data in
page fragments) while skb_gro_offset is non-zero (after IP+TCP header
parsing). The skb_pull() then decrements skb->len by skb_gro_offset
but skb->data_len stays unchanged, hitting BUG_ON(skb->len < skb->data_len)
in __skb_pull().

The UDP fraglist GRO path already contains this guard at
udp_offload.c:749. Adding it to skb_gro_receive_list() itself provides
centralized protection for all callers (TCP, UDP, and any future
protocols), and ensures the precondition of skb_pull() is satisfied
before it is called.

On pskb_may_pull() failure, set NAPI_GRO_CB(skb)->flush = 1 so the
skb is not held as a new GRO head and is instead delivered through the
normal receive path, matching the UDP handling.

Fixes: 8d95dc474f85 ("net: add code for TCP fraglist GRO")
Reported-by: HanQuan 
Reported-by: MingXuan 
Signed-off-by: HanQuan 
Reviewed-by: Eric Dumazet 
Signed-off-by: Jakub Kicinski

tcp: restrict SO_ATTACH_FILTER to priv users

2026-06-08T22:37:10+00:00

This patch restricts the use of SO_ATTACH_FILTER (cBPF) on TCP sockets
to users with CAP_NET_ADMIN capability.

This blocks potential side-channel attack where an unprivileged application
attaches a filter to leak TCP sequence/acknowledgment numbers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet 
Reported-by: Tamir Shahar 
Reported-by: Amit Klein 
Cc: Willem de Bruijn 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Andrii Nakryiko 
Cc: Martin KaFai Lau 
Cc: Eduard Zingerman 
Cc: Kumar Kartikeya Dwivedi 
Cc: Song Liu 
Cc: Yonghong Song 
Cc: Jiri Olsa 
Cc: John Fastabend 
Cc: Stanislav Fomichev 
Acked-by: Daniel Borkmann 
Reviewed-by: Willem de Bruijn 
Signed-off-by: Jakub Kicinski

net: Annotate sk->sk_write_space() for UDP SOCKMAP.

2026-06-02T18:44:43+00:00

UDP TX skb->destructor() is sock_wfree(), and UDP holds lock_sock()
only for UDP_CORK / MSG_MORE sendmsg().

Otherwise, sk->sk_write_space() may be read locklessly while SOCKMAP
rewrites sk->sk_write_space().

Let's use WRITE_ONCE() and READ_ONCE() for sk->sk_write_space().

Note that the write side is annotated by commit 2ef2b20cf4e0
("net: annotate data-races around sk->sk_{data_ready,write_space}").

Fixes: 7b98cd42b049 ("bpf: sockmap: Add UDP support")
Signed-off-by: Kuniyuki Iwashima 
Reviewed-by: Jakub Sitnicki 
Link: https://patch.msgid.link/20260529193941.3897256-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski

net: skbuff: fix pskb_carve leaking zcopy pages

2026-05-29T19:55:27+00:00

When SKBFL_MANAGED_FRAG_REFS is set, frag pages are not refcounted but
their lifetime is controlled by the attached ubuf_info. To make a copy
of the skb_shared_info, we either should clear the flag and reference
the frags, or keep the flag and have frags unreferenced.

pskb_carve_inside_header() and pskb_carve_inside_nonlinear() don't
follow the rule and thus can leak page references. Let's clear
SKBFL_MANAGED_FRAG_REFS from the original skb to fix it. It's the
simplest way to address it, but there are more performant ways to do
that if it ever becomes a problem.

Link: https://lore.kernel.org/all/20260523085809.26331-1-nvminh232@clc.fitus.edu.vn/
Fixes: 753f1ca4e1e50 ("net: introduce managed frags infrastructure")
Reported-by: Minh Nguyen 
Reported-by: Willem de Bruijn 
Signed-off-by: Pavel Begunkov 
Reviewed-by: Willem de Bruijn 
Link: https://patch.msgid.link/1e2086aa69217d7f9c8da3d38f5be7160f1b4cd1.1779993185.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski

bpf: sockmap: fix tail fragment offset in bpf_msg_push_data

2026-05-29T19:38:35+00:00

When bpf_msg_push_data() inserts data in the middle of a scatterlist
entry, it splits the original entry into a left fragment and a right
fragment.

The right fragment offset is page-local, but the code advances it with
`start`, which is the message-global insertion point. For inserts into a
non-first SG entry, this over-advances the offset and leaves the split
layout inconsistent.

Advance the right fragment offset by the fragment-local delta,
`start - offset`, which matches the length removed from the front of the
original entry.

Fixes: 6fff607e2f14 ("bpf: sk_msg program helper bpf_msg_push_data")
Cc: stable@kernel.org
Reported-by: Yuan Tan 
Reported-by: Zhengchuan Liang 
Reported-by: Xin Liu 
Signed-off-by: Yuqi Xu 
Signed-off-by: Ren Wei 
Link: https://patch.msgid.link/8b129d10566aa3eb43f61a8f9757bcf51707d324.1779636774.git.xuyq21@lenovo.com
Signed-off-by: Jakub Kicinski