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Ilya Maximets ea966b6698 openvswitch: fix lockup on tx to unregistering netdev with carrier 
[ Upstream commit 47e55e4b41 ]

Commit in a fixes tag attempted to fix the issue in the following
sequence of calls:

    do_output
    -> ovs_vport_send
       -> dev_queue_xmit
          -> __dev_queue_xmit
             -> netdev_core_pick_tx
                -> skb_tx_hash

When device is unregistering, the 'dev->real_num_tx_queues' goes to
zero and the 'while (unlikely(hash >= qcount))' loop inside the
'skb_tx_hash' becomes infinite, locking up the core forever.

But unfortunately, checking just the carrier status is not enough to
fix the issue, because some devices may still be in unregistering
state while reporting carrier status OK.

One example of such device is a net/dummy.  It sets carrier ON
on start, but it doesn't implement .ndo_stop to set the carrier off.
And it makes sense, because dummy doesn't really have a carrier.
Therefore, while this device is unregistering, it's still easy to hit
the infinite loop in the skb_tx_hash() from the OVS datapath.  There
might be other drivers that do the same, but dummy by itself is
important for the OVS ecosystem, because it is frequently used as a
packet sink for tcpdump while debugging OVS deployments.  And when the
issue is hit, the only way to recover is to reboot.

Fix that by also checking if the device is running.  The running
state is handled by the net core during unregistering, so it covers
unregistering case better, and we don't really need to send packets
to devices that are not running anyway.

While only checking the running state might be enough, the carrier
check is preserved.  The running and the carrier states seem disjoined
throughout the code and different drivers.  And other core functions
like __dev_direct_xmit() check both before attempting to transmit
a packet.  So, it seems safer to check both flags in OVS as well.

Fixes: 066b86787f ("net: openvswitch: fix race on port output")
Reported-by: Friedrich Weber <f.weber@proxmox.com>
Closes: https://mail.openvswitch.org/pipermail/ovs-discuss/2025-January/053423.html
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Tested-by: Friedrich Weber <f.weber@proxmox.com>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20250109122225.4034688-1-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-01-23 17:21:09 +01:00
arch riscv: Fix text patching when IPI are used 2025-01-17 13:36:26 +01:00
block block, bfq: fix waker_bfqq UAF after bfq_split_bfqq() 2025-01-17 13:36:25 +01:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: ecc - Prevent ecc_digits_from_bytes from reading too many bytes 2025-01-09 13:31:52 +01:00
Documentation dt-bindings: display: adi,adv7533: Drop single lane support 2025-01-09 13:32:08 +01:00
drivers net: ethernet: ti: cpsw_ale: Fix cpsw_ale_get_field() 2025-01-23 17:21:09 +01:00
fs Revert "ovl: do not encode lower fh with upper sb_writers held" 2025-01-21 09:49:10 +01:00
include mm: hugetlb: independent PMD page table shared count 2025-01-17 13:36:26 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-09 10:32:46 +01:00
io_uring io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period 2025-01-17 13:36:24 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-09 10:32:54 +01:00
kernel workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker 2025-01-17 13:36:25 +01:00
lib seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str() 2025-01-09 13:31:55 +01:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: hugetlb: independent PMD page table shared count 2025-01-17 13:36:26 +01:00
net openvswitch: fix lockup on tx to unregistering netdev with carrier 2025-01-23 17:21:09 +01:00
rust rust: macros: fix documentation of the paste! macro 2024-12-09 10:32:25 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 20:00:03 +01:00
scripts scripts/sorttable: fix orc_sort_cmp() to maintain symmetry and transitivity 2025-01-09 13:32:07 +01:00
security selinux: ignore unknown extended permissions 2025-01-09 13:31:54 +01:00
sound ASoC: mediatek: disable buffer pre-allocation 2025-01-17 13:36:11 +01:00
tools memblock tests: fix implicit declaration of function 'numa_valid_node' 2025-01-17 13:36:14 +01:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.73 2025-01-21 09:49:10 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.