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Filename Latest commit message Latest commit date
Josef Bacik 7bbf647dbb btrfs: only search for left_info if there is no right_info in try_merge_free_space
commit bf53d4687b8f3f6b752f091eb85f62369a515dfd upstream.

In try_to_merge_free_space we attempt to find entries to the left and
right of the entry we are adding to see if they can be merged.  We
search for an entry past our current info (saved into right_info), and
then if right_info exists and it has a rb_prev() we save the rb_prev()
into left_info.

However there's a slight problem in the case that we have a right_info,
but no entry previous to that entry.  At that point we will search for
an entry just before the info we're attempting to insert.  This will
simply find right_info again, and assign it to left_info, making them
both the same pointer.

Now if right_info _can_ be merged with the range we're inserting, we'll
add it to the info and free right_info.  However further down we'll
access left_info, which was right_info, and thus get a use-after-free.

Fix this by only searching for the left entry if we don't find a right
entry at all.

The CVE referenced had a specially crafted file system that could
trigger this use-after-free. However with the tree checker improvements
we no longer trigger the conditions for the UAF.  But the original
conditions still apply, hence this fix.

Reference: CVE-2019-19448
Fixes: 9630308170 ("Btrfs: use hybrid extents+bitmap rb tree for free space")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-21 13:05:23 +02:00
arch genirq/affinity: Make affinity setting if activated opt-in 2020-08-21 13:05:20 +02:00
block iocost: Fix check condition of iocg abs_vdebt 2020-08-19 08:15:58 +02:00
certs
crypto keys: asymmetric: fix error return code in software_key_query() 2020-07-22 09:33:04 +02:00
Documentation iio: improve IIO_CONCENTRATION channel type description 2020-08-19 08:16:07 +02:00
drivers PCI: qcom: Add support for tx term offset for rev 2.1.0 2020-08-21 13:05:20 +02:00
fs btrfs: only search for left_info if there is no right_info in try_merge_free_space 2020-08-21 13:05:23 +02:00
include genirq/affinity: Make affinity setting if activated opt-in 2020-08-21 13:05:20 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc
kernel genirq/PM: Always unlock IRQ descriptor in rearm_wake_irq() 2020-08-21 13:05:20 +02:00
lib kobject: Avoid premature parent object freeing in kobject_cleanup() 2020-08-19 08:16:11 +02:00
LICENSES
mm mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls 2020-08-19 08:16:02 +02:00
net net: initialize fastreuse on inet_inherit_port 2020-08-19 08:16:23 +02:00
samples bpf: Fix fds_example SIGSEGV error 2020-08-19 08:16:03 +02:00
scripts recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64. 2020-08-19 08:15:57 +02:00
security Smack: prevent underflow in smk_set_cipso() 2020-08-19 08:16:16 +02:00
sound ALSA: usb-audio: add quirk for Pioneer DDJ-RB 2020-08-19 08:16:27 +02:00
tools tools, bpftool: Fix wrong return value in do_dump() 2020-08-19 08:16:19 +02:00
usr
virt KVM: arm64: Don't inherit exec permission across page-table levels 2020-08-05 09:59:51 +02:00
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Makefile Linux 5.4.59 2020-08-19 08:16:29 +02:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.