Go to file
Matthew Ahrens 43186f94f4 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
2020-09-16 14:17:32 -07:00
.github Fix typos 2020-01-22 13:49:00 -08:00
cmd Fix gcc 10.1 stringop-truncation error 2020-09-15 21:16:58 +00:00
config Linux 5.9 compat: NR_SLAB_RECLAIMABLE (#10865) 2020-09-15 21:16:58 +00:00
contrib Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
etc Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
include Appease GCC sprintf warnings found on Fedora 32/GCC 10.0.1 2020-09-15 23:43:12 +00:00
lib Appease GCC sprintf warnings found on Fedora 32/GCC 10.0.1 2020-09-15 23:43:12 +00:00
man ICP: Improve AES-GCM performance 2020-05-12 10:53:32 -07:00
module Fix lua stack overflow on recursive call to gsub() 2020-09-16 14:17:32 -07:00
rpm lib/libzfs, rpm: Install pkgconfig files in the correct directory (#10628) 2020-09-15 21:16:58 +00:00
scripts Fix typos 2020-01-22 13:49:00 -08:00
tests Fix lua stack overflow on recursive call to gsub() 2020-09-16 14:17:32 -07:00
udev Restore :: in Makefile.am 2020-05-12 10:53:32 -07:00
.gitignore Adapt gitignore for modules 2020-01-22 13:49:05 -08:00
.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 Linux 5.9 compat: add linux/blkdev.h include 2020-09-15 21:16:58 +00:00
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 Fix zfs-functions packaging bug 2020-05-12 10:53:32 -07:00
copy-builtin Allow copy-builtin to work with modified sources 2018-10-17 12:06:05 -07:00
COPYRIGHT ICP: Improve AES-GCM performance 2020-05-12 10:53:32 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am Perform KABI checks in parallel 2020-01-22 13:49:01 -08:00
META Tag zfs-0.8.4 2020-05-12 10:53:32 -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 Explicitly state supported Linux versions 2018-05-30 20:11:19 -07:00
TEST Update build system and packaging 2018-05-29 16:00:33 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

img

ZFS on Linux is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community.

codecov coverity

Official Resources

Installation

Full documentation for installing ZoL on your favorite Linux distribution can be found at our site.

Contribute & Develop

We have a separate document with contribution guidelines.

Release

ZFS on Linux 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 kernel versions.