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Amaury Denoyelle 50ae717624 BUG/MEDIUM: server: fix race on server_atomic_sync() 
The following patch fixes a race condition during server addr/port
update :
  cd994407a9
  BUG/MAJOR: server/addr: fix a race during server addr:svc_port updates

The new update mechanism is implemented via an event update. It uses
thread isolation to guarantee that no other thread is accessing server
addr/port. Furthermore, to ensure server instance is not deleted just
before the event handler, server instance is lookup via its ID in proxy
tree.

However, thread isolation is only entered after server lookup. This
leaves a tiny race condition as the thread will be marked as harmless
and a concurrent thread can delete the server in the meantime. This
causes server_atomic_sync() to manipulated a deleted server instance to
reinsert it in used_server_addr backend tree. This can cause a segfault
during this operation or possibly on a future used_server_addr tree
access.

This issue was detected by criteo. Several backtraces were retrieved,
each related to server addr_node insert or delete operation, either in
srv_set_addr_desc(), or add/delete dynamic server handlers.

To fix this, simply extend thread isolation section to start it before
server lookup. This ensures that once retrieved the server cannot be
deleted until its addr/port are updated. To ensure this issue won't
happen anymore, a new BUG_ON() is added in srv_set_addr_desc().

Also note that ebpt_delete() is now called every time on delete handler
as this is a safe idempotent operation.

To reproduce these crashes, a script was executed to add then remove
different servers every second. In parallel, the following CLI command
was issued repeatdly without any delay to force multiple update on
servers port :

  set server <srv> addr 0.0.0.0 port $((1024 + RANDOM % 1024))

This must be backported at least up to 3.0. If above mentionned patch
has been selected for previous version, this commit must also be
backported on them.
2024-07-03 09:20:24 +02:00
.github CI: github: do the AWS-LC weekly build with ERR=1 2024-06-14 12:18:32 +02:00
addons BUG/MINOR: promex: Remove Help prefix repeated twice for each metric 2024-07-01 10:50:27 +02:00
admin ADMIN: acme.sh: remove the old acme.sh code 2024-05-31 13:37:47 +02:00
dev DEV: flags/show-fd-to-flags: adapt to recent versions 2024-06-25 08:13:24 +02:00
doc DOC: configuration: more details about the master-worker mode 2024-07-02 18:23:34 +02:00
examples CLEANUP: assorted typo fixes in the code and comments 2023-11-23 16:23:14 +01:00
include BUG/MEDIUM: h3: ensure the ":method" pseudo header is totally valid 2024-06-28 14:36:30 +02:00
reg-tests REGTESTS: ssl: activate new SSL reg-tests with AWS-LC 2024-06-17 17:43:22 +02:00
scripts SCRIPTS: git-show-backports: do not truncate git-show output 2024-06-21 15:08:42 +02:00
src BUG/MEDIUM: server: fix race on server_atomic_sync() 2024-07-03 09:20:24 +02:00
tests MINOR: ist: define iststrip() new function 2024-04-26 11:29:25 +02:00
.cirrus.yml CI: FreeBSD: upgrade image, packages 2024-06-04 11:19:00 +02:00
.gitattributes MINOR: Configure the cpp userdiff driver for *.[ch] in .gitattributes 2021-02-22 18:17:57 +01:00
.gitignore CONTRIB: Add vi file extensions to .gitignore 2023-06-02 18:14:34 +02:00
.mailmap DOC: update Tim's address in .mailmap 2021-09-16 09:14:14 +02:00
.travis.yml CI: travis-ci: temporarily disable arm64 builds 2021-08-07 07:28:15 +02:00
BRANCHES DOC: fix some spelling issues over multiple files 2021-01-08 14:53:47 +01:00
BSDmakefile BUILD: makefile: commit the tiny FreeBSD makefile stub 2023-05-24 17:17:36 +02:00
CHANGELOG [RELEASE] Released version 3.1-dev2 2024-06-29 11:28:41 +02:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
INSTALL DOC: INSTALL: minimum AWS-LC version is v1.22.0 2024-06-14 12:06:03 +02:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS MAJOR: spoe: Let the SPOE back into the game 2024-05-22 09:04:38 +02:00
Makefile REORG: ssl: move the SNI selection code in ssl_clienthello.c 2024-06-13 16:48:17 +02:00
README.md DOC: change the link to the FreeBSD CI in README.md 2024-06-03 15:21:29 +02:00
SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 3.1-dev2 2024-06-29 11:28:41 +02:00
VERSION [RELEASE] Released version 3.1-dev2 2024-06-29 11:28:41 +02:00

README.md

HAProxy

alpine/musl AWS-LC openssl no-deprecated Illumos NetBSD FreeBSD VTest

HAProxy logo

HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

Installation

The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.

Getting help

The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.

The issue tracker is only for bug reports or feature requests.

Documentation

The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.

Please refer to the following files depending on what you're looking for:

  • INSTALL for instructions on how to build and install HAProxy
  • BRANCHES to understand the project's life cycle and what version to use
  • LICENSE for the project's license
  • CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory:

License

HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.