mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-09-22 09:34:56 +02:00
Yizhou Zhao
bca4bfb9cc
commitb06163ce52upstream. ecache_work_evict_list() redelivers DESTROY events for conntracks that were moved to the per-netns dying_list after event delivery failed. It sets a 10ms deadline: stop = jiffies + ECACHE_MAX_JIFFIES but then tests: time_after(stop, jiffies) This condition is true while the deadline is still in the future, so the worker returns STATE_RESTART after the first successful redelivery in the usual case. ecache_work() maps STATE_RESTART to delay 0, which turns the redelivery path into one dying conntrack per workqueue dispatch and makes the sent > 16 batching/cond_resched() path effectively unreachable. A conntrack netlink listener whose receive queue is congested can make DESTROY event delivery fail with -ENOBUFS. With sustained conntrack churn, entries then accumulate on the dying_list and are only drained at the degraded one-entry-per-dispatch rate once delivery succeeds again, wasting CPU on back-to-back workqueue reschedules and prolonging conntrack memory/resource pressure. In a KASAN QEMU test with CONFIG_NF_CONNTRACK_EVENTS=y and nf_conntrack.enable_hooks=1, a congested DESTROY listener caused 8192 nf_ct_delete() calls to return false and move entries to the dying_list. After closing the listener, the unfixed kernel needed 7670 ecache_work() entries to destroy 7669 conntracks. With this change, the same 8192 entries were destroyed by 2 ecache_work() entries. Swap the comparison so the worker restarts only after the deadline has expired. Fixes:2ed3bf188b("netfilter: ecache: use dedicated list for event redelivery") Cc: stable@vger.kernel.org Reported-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn> Reported-by: Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn> Reported-by: Ao Wang <wangao@seu.edu.cn> Reported-by: Xuewei Feng <fengxw06@126.com> Reported-by: Qi Li <qli01@tsinghua.edu.cn> Reported-by: Ke Xu <xuke@tsinghua.edu.cn> Assisted-by: Claude-Code:GLM-5.2 Signed-off-by: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.