freebsd kernel with SKQ
ed042b9725
Fix a buffer overrun which may lead to data corruption, introduced in
r286951 by reinstating changes in r274628.
In l2arc_compress_buf(), we allocate a buffer to stash away the compressed
data in 'cdata', allocated of l2hdr->b_asize bytes.
We then ask zio_compress_data() to compress the buffer, b_l1hdr.b_tmp_cdata,
which is of l2hdr->b_asize bytes, and have the compressed size (or original
size, if compress didn't gain enough) stored in csize.
To pad the buffer to fit the optimal write size, we round up the compressed
size to L2 device's vdev_ashift.
Illumos code rounds up the size by at most SPA_MINBLOCKSIZE. Because we
know csize <= b_asize, and b_asize is integer multiple of SPA_MINBLOCKSIZE,
we are guaranteed that the rounded up csize would be <= b_asize. However,
this is not necessarily true when we round up to 1 << vdev_ashift, because
it could be larger than SPA_MINBLOCKSIZE.
So, in the worst case scenario, we are overwriting at most
(1 << vdev_ashift - SPA_MINBLOCKSIZE)
bytes of memory next to the compressed data buffer.
Andriy's original change in r274628 reorganized the code a little bit,
by moving the padding to after we determined that the compression was
beneficial. At which point, we would check rounded size against the
allocated buffer size, and the buffer overrun would not be possible.
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| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html