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Matthew Ahrens 3eabed74c0
Fix lua stack overflow on recursive call to gsub()
The `zfs program` subcommand invokes a LUA interpreter to run ZFS
"channel programs".  This interpreter runs in a constrained environment,
with defined memory limits.  The LUA stack (used for LUA functions that
call each other) is allocated in the kernel's heap, and is limited by
the `-m MEMORY-LIMIT` flag and the `zfs_lua_max_memlimit` module
parameter.  The C stack is used by certain LUA features that are
implemented in C.  The C stack is limited by `LUAI_MAXCCALLS=20`, which
limits call depth.

Some LUA C calls use more stack space than others, and `gsub()` uses an
unusually large amount.  With a programming trick, it can be invoked
recursively using the C stack (rather than the LUA stack).  This
overflows the 16KB Linux kernel stack after about 11 iterations, less
than the limit of 20.

One solution would be to decrease `LUAI_MAXCCALLS`.  This could be made
to work, but it has a few drawbacks:

1. The existing test suite does not pass with `LUAI_MAXCCALLS=10`.

2. There may be other LUA functions that use a lot of stack space, and
the stack space may change depending on compiler version and options.

This commit addresses the problem by adding a new limit on the amount of
free space (in bytes) remaining on the C stack while running the LUA
interpreter: `LUAI_MINCSTACK=4096`.  If there is less than this amount
of stack space remaining, a LUA runtime error is generated.

Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Allan Jude <allanjude@freebsd.org>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #10611 
Closes #10613
2020-07-27 16:11:47 -07:00
.github OpenZFSify CONTRIBUTING.md 2020-07-22 11:09:04 -07:00
cmd Add support to decode a resume token 2020-07-23 17:44:03 -07:00
config Linux 4.10 compat: has_capability() 2020-07-19 09:56:21 -07:00
contrib Centralize variable substitution 2020-07-14 17:33:44 -07:00
etc Make unloading the key more robust 2020-07-19 10:04:14 -07:00
include Refactor ccompile.h to not include system headers 2020-07-25 20:09:50 -07:00
lib FreeBSD: Fixes required to build ZFS on PowerPC 2020-07-25 11:00:23 -07:00
man Limit dbuf cache sizes based only on ARC target size by default 2020-07-24 20:38:48 -07:00
module Fix lua stack overflow on recursive call to gsub() 2020-07-27 16:11:47 -07:00
rpm Disable shebang mangling on input files 2020-07-19 10:19:08 -07:00
scripts Add zfs_gitrev.h to the distributed sources 2020-07-22 10:00:40 -07:00
tests Fix lua stack overflow on recursive call to gsub() 2020-07-27 16:11:47 -07:00
udev Centralize variable substitution 2020-07-14 17:33:44 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
.travis.yml Add .travis.yml 2017-11-13 09:18:18 -08:00
AUTHORS Update build system and packaging 2018-05-29 16:00:33 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
CODE_OF_CONDUCT.md Add CODE_OF_CONDUCT.md 2019-04-30 10:58:45 -07:00
configure.ac Clean up lib dependencies 2020-07-10 14:26:00 -07:00
copy-builtin Move zfs_gitrev.h to build directory 2020-06-24 18:19:28 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
cppcheck-suppressions.txt Move cppcheck suppressions out of .github 2020-06-27 17:40:15 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Add zfs_gitrev.h to the distributed sources 2020-07-22 10:00:40 -07:00
META Linux 5.7 compat: blk_alloc_queue() 2020-04-09 09:16:46 -07:00
NEWS Add NEWS file 2018-09-18 12:03:47 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md Update wiki links with new address 2020-06-03 19:46:31 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite Linux distribution can be found at the ZoL Site.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are 12-STABLE and 13-CURRENT.