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Filename Latest commit message Latest commit date
Stanislav Fomichev e1d41cb9c0 net: set SOCK_RCU_FREE before inserting socket into hashtable
commit 871019b22d1bcc9fab2d1feba1b9a564acbb6e99 upstream.

We've started to see the following kernel traces:

 WARNING: CPU: 83 PID: 0 at net/core/filter.c:6641 sk_lookup+0x1bd/0x1d0

 Call Trace:
  <IRQ>
  __bpf_skc_lookup+0x10d/0x120
  bpf_sk_lookup+0x48/0xd0
  bpf_sk_lookup_tcp+0x19/0x20
  bpf_prog_<redacted>+0x37c/0x16a3
  cls_bpf_classify+0x205/0x2e0
  tcf_classify+0x92/0x160
  __netif_receive_skb_core+0xe52/0xf10
  __netif_receive_skb_list_core+0x96/0x2b0
  napi_complete_done+0x7b5/0xb70
  <redacted>_poll+0x94/0xb0
  net_rx_action+0x163/0x1d70
  __do_softirq+0xdc/0x32e
  asm_call_irq_on_stack+0x12/0x20
  </IRQ>
  do_softirq_own_stack+0x36/0x50
  do_softirq+0x44/0x70

__inet_hash can race with lockless (rcu) readers on the other cpus:

  __inet_hash
    __sk_nulls_add_node_rcu
    <- (bpf triggers here)
    sock_set_flag(SOCK_RCU_FREE)

Let's move the SOCK_RCU_FREE part up a bit, before we are inserting
the socket into hashtables. Note, that the race is really harmless;
the bpf callers are handling this situation (where listener socket
doesn't have SOCK_RCU_FREE set) correctly, so the only
annoyance is a WARN_ONCE.

More details from Eric regarding SOCK_RCU_FREE timeline:

Commit 3b24d854cb ("tcp/dccp: do not touch listener sk_refcnt under
synflood") added SOCK_RCU_FREE. At that time, the precise location of
sock_set_flag(sk, SOCK_RCU_FREE) did not matter, because the thread calling
__inet_hash() owns a reference on sk. SOCK_RCU_FREE was only tested
at dismantle time.

Commit 6acc9b432e ("bpf: Add helper to retrieve socket in BPF")
started checking SOCK_RCU_FREE _after_ the lookup to infer whether
the refcount has been taken care of.

Fixes: 6acc9b432e ("bpf: Add helper to retrieve socket in BPF")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[Resolved conflict for 5.10 and below.]
Signed-off-by: Siddh Raman Pant <siddh.raman.pant@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-09-12 11:03:50 +02:00
arch openrisc: Call setup_memory() earlier in the init sequence 2024-09-04 13:14:57 +02:00
block block: initialize integrity buffer to zero before writing it to media 2024-09-12 11:03:50 +02:00
certs
crypto crypto: ecrdsa - Fix module auto-load on add_key 2024-06-16 13:28:51 +02:00
Documentation overflow: Implement size_t saturating arithmetic helpers 2024-09-04 13:14:51 +02:00
drivers media: uvcvideo: Enforce alignment of frame and interval 2024-09-12 11:03:50 +02:00
fs filelock: Correct the filelock owner in fcntl_setlk/fcntl_setlk64 2024-09-04 13:15:02 +02:00
include i2c: Fix conditional for substituting empty ACPI functions 2024-09-12 11:03:49 +02:00
init init: open /initrd.image with O_LARGEFILE 2024-04-13 12:51:36 +02:00
ipc ipc: replace costly bailout check in sysvipc_find_ipc() 2024-09-04 13:15:02 +02:00
kernel cgroup/cpuset: Prevent UAF in proc_cpuset_show() 2024-09-04 13:15:03 +02:00
lib overflow: Implement size_t saturating arithmetic helpers 2024-09-04 13:14:51 +02:00
LICENSES
mm memcg_write_event_control(): fix a user-triggerable oops 2024-09-04 13:14:50 +02:00
net net: set SOCK_RCU_FREE before inserting socket into hashtable 2024-09-12 11:03:50 +02:00
samples media: rename VFL_TYPE_GRABBER to _VIDEO 2024-03-26 18:22:22 -04:00
scripts kbuild: Fix '-S -c' in x86 stack protector scripts 2024-08-19 05:33:53 +02:00
security smack: tcp: ipv4, fix incorrect labeling 2024-09-12 11:03:50 +02:00
sound ALSA: timer: Relax start tick time check for slave timer elements 2024-09-04 13:15:01 +02:00
tools tools: move alignment-related macros to new <linux/align.h> 2024-09-04 13:15:02 +02:00
usr
virt KVM: async_pf: Cleanup kvm_setup_async_pf() 2024-05-02 16:18:32 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.283 2024-09-04 13:15:05 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.