upstream/haproxy
1
0
Fork 0
mirror of https://github.com/haproxy/haproxy.git synced 2026-02-19 02:29:31 -05:00
Code Issues Projects Releases Packages Wiki Activity Actions 18
HAProxy - Load balancer
16028 commits 28 branches 408 tags 304 MiB
C 98.1%
Shell 0.9%
Makefile 0.5%
Lua 0.2%
Python 0.1%
Find a file
Willy Tarreau fdf53b4962 BUG/MINOR: pools: don't mark ourselves as harmless in DEBUG_UAF mode 
When haproxy is built with DEBUG_UAF=1, some particularly slow
allocation functions are used for each pool, and it was not uncommon
to see the watchdog trigger during performance tests. For this reason
the allocation functions were surrounded by a pair of thread_harmless
calls to mention that the function was waiting in slow syscalls. The
problem is that this also releases functions blocked in thread_isolate()
which can then start their work.

In order to protect against the accidental removal of a shared resource
in this situation, in 2.5-dev4 with commit ba3ab7907 ("MEDIUM: servers:
make the server deletion code run under full thread isolation") was added
thread_isolate_full() for functions which want to be totally protected
due to being manipulating some data.

But this is not sufficient, because there are still places where we
can allocate/free (thus sleep) under a lock, such as in long call
chains involving the release of an idle connection. In this case, if
one thread asks for isolation, one thread might hang in
pool_alloc_area_uaf() with a lock held (for example the conns_lock
when coming from conn_backend_get()->h1_takeover()->task_new()), with
another thread blocked on a lock waiting for that one to release it,
both keeping their bit clear in the thread_harmless mask, preventing
the first thread from being released, thus causing a deadlock.

In addition to this, it was already seen that the "show fd" CLI handler
could wake up during a pool_free_area_uaf() with an incompletely
released memory area while deleting a file descriptor, and be fooled
showing bad pointers, or during a pool_alloc() on another thread that
was in the process of registering a freshly allocated connection to a
new file descriptor.

One solution could consist in replacing all thread_isolate() calls by
thread_isolate_full() but then that makes thread_isolate() useless
and only shifts the problem by one slot.

A better approach could possibly consist in having a way to mark that
a thread is entering an extremely slow section. Such sections would
be timed so that this is not abused, and the bit would be used to
make the watchdog more patient. This would be acceptable as this would
only affect debugging.

The approach used here for now consists in removing the harmless bits
around the UAF allocator, thus essentially undoing commit 85b2cae63
("MINOR: pools: make the thread harmless during the mmap/munmap
syscalls").

This is marked as minor because nobody is expected to be running with
DEBUG_UAF outside of development or serious debugging, so this issue
cannot affect regular users. It must be backported to stable branches
that have thread_harmless_now() around the mmap() call.
2021-11-12 11:17:37 +01:00
.github CI: Clean up formatting in GitHub Action definitions 2021-10-18 07:17:04 +02:00
addons MINOR: promex: backend aggregated server check status 2021-11-09 10:51:08 +01:00
admin OPTIM: halog: skip fields 64 bits at a time when supported 2021-11-08 12:08:26 +01:00
dev Revert "DEV: coccinelle: Add rule to use chunk_istcat() instead of chunk_strncat()" 2021-11-08 13:42:03 +01:00
doc DOC: management: edit the "show proc" example to show the current output 2021-11-10 15:53:01 +01:00
examples MEDIUM: proxy: remove long-broken 'option http_proxy' 2021-07-18 19:35:32 +02:00
include MINOR: mworker: implement a reload failure counter 2021-11-10 15:53:01 +01:00
reg-tests REGTESTS: httpclient/lua: add greater body values 2021-11-10 17:40:19 +01:00
scripts SCRIPTS: git-show-backports: re-enable file-based filtering 2021-11-03 08:41:01 +01:00
src BUG/MINOR: pools: don't mark ourselves as harmless in DEBUG_UAF mode 2021-11-12 11:17:37 +01:00
tests CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
.cirrus.yml CI: introduce scripts/build-vtest.sh for installing VTest 2021-05-18 10:48:30 +02:00
.gitattributes MINOR: Configure the cpp userdiff driver for *.[ch] in .gitattributes 2021-02-22 18:17:57 +01:00
.gitignore DOC: lua-api: Add documentation about lua filters 2021-08-15 20:56:44 +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
CHANGELOG [RELEASE] Released version 2.5-dev13 2021-11-06 09:25:57 +01:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
INSTALL DOC: add QUIC instruction in INSTALL 2021-11-03 18:32:22 +01:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS CONTRIB: move spoa_example out of the tree 2021-04-21 09:39:06 +02:00
Makefile MINOR: jwt: Parse JWT alg field 2021-10-14 16:38:08 +02:00
README DOC: create a BRANCHES file to explain the life cycle 2019-06-15 22:00:14 +02:00
ROADMAP DOC: update the outdated ROADMAP file 2019-06-15 21:59:54 +02:00
SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 2.5-dev13 2021-11-06 09:25:57 +01:00
VERSION [RELEASE] Released version 2.5-dev13 2021-11-06 09:25:57 +01:00

README 

The HAProxy documentation has been split into a number of different files for
ease of use.

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 :

  - doc/intro.txt for a quick introduction on HAProxy
  - doc/configuration.txt for the configuration's reference manual
  - doc/lua.txt for the Lua's reference manual
  - doc/SPOE.txt for how to use the SPOE engine
  - doc/network-namespaces.txt for how to use network namespaces under Linux
  - doc/management.txt for the management guide
  - doc/regression-testing.txt for how to use the regression testing suite
  - doc/peers.txt for the peers protocol reference
  - doc/coding-style.txt for how to adopt HAProxy's coding style
  - doc/internals for developer-specific documentation (not all up to date)