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Willy Tarreau d069825c5f BUG/MEDIUM: mux-fcgi: fail earlier on malloc in takeover()
This is the equivalent of the previous "BUG/MEDIUM: mux-h1: fail earlier
on malloc in takeover()".

Connection takeover was implemented for fcgi in 2.2 by commit a41bb0b6c
("MEDIUM: mux_fcgi: Implement the takeover() method."). It does have one
corner case related to memory allocation failure: in case the task or
tasklet allocation fails, the connection gets released synchronously.

Unfortunately the situation is bad there, because the lower layers are
already switched to the new thread while the tasklet is either NULL or
still the old one, and calling fcgi_release() will also result in
touching the thread-local list of buffer waiters, calling unsubscribe(),
There are even code paths where the thread will try to grab the lock of
its own idle conns list, believing the connection is there while it has
no useful effect. However, if the owner thread was doing the same at the
same moment, and ended up trying to pick from the current thread (which
could happen if picking a connection for a different name), the two
could even deadlock.

No tests were made to try to reproduce the problem, but the description
above is sufficient to see that nothing can guarantee against it.

This patch takes a simple but radically different approach. Instead of
starting to migrate the connection before risking to face allocation
failures, it first pre-allocates a new task and tasklet, then assigns
them to the connection if the migration succeeds, otherwise it just
frees them. This way it's no longer needed to manipulate the connection
until it's fully migrated, and as a bonus this means the connection will
continue to exist and the use-after-free condition is solved at the same
time.

This should be backported to 2.2. Thanks to Fred for the initial analysis
of the problem!
2023-11-17 18:10:16 +01:00
.github CI: github: update wolfSSL to 5.6.4 2023-11-03 18:50:45 +01:00
addons MEDIUM: tree-wide: logsrv struct becomes logger 2023-10-13 10:05:06 +02:00
admin MEDIUM: systemd: be more verbose about the reload 2023-10-31 18:59:29 +01:00
dev DEV: sslkeylogger: handle file opening error 2023-10-03 15:23:35 +02:00
doc MINOR: quic: Rename "handshake" timeout to "client-hs" 2023-11-17 18:09:41 +01:00
examples EXAMPLES: maintain haproxy 2.8 retrocompatibility for lua mailers script 2023-07-11 16:04:22 +02:00
include MINOR: quic: Rename "handshake" timeout to "client-hs" 2023-11-17 18:09:41 +01:00
reg-tests REGTESTS: try to activate again the seamless reload test with the master CLI 2023-11-17 17:11:42 +01:00
scripts CI: ssl: add git id support for wolfssl download 2023-10-10 10:34:17 +02:00
src BUG/MEDIUM: mux-fcgi: fail earlier on malloc in takeover() 2023-11-17 18:10:16 +01:00
tests Revert "MAJOR: import: update mt_list to support exponential back-off" 2023-09-15 17:13:43 +02:00
.cirrus.yml CI: cirrus-ci: display gdb bt if any 2023-09-22 08:28:30 +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 2.9-dev9 2023-11-04 09:38:16 +01:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2021-08-16 12:37:59 +02:00
INSTALL DOC: install: update the wolfSSL required version 2023-11-03 19:02:23 +01:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS CLEANUP: assorted typo fixes in the code and comments 2022-11-30 14:02:36 +01:00
Makefile BUILD: ssl: Build with new cryptographic library AWS-LC 2023-09-04 18:19:18 +02:00
README DOC: create a BRANCHES file to explain the life cycle 2019-06-15 22:00:14 +02:00
SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 2.9-dev9 2023-11-04 09:38:16 +01:00
VERSION [RELEASE] Released version 2.9-dev9 2023-11-04 09:38:16 +01:00

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)