kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-20 19:23:40 +00:00
Code Issues Releases Packages Activity
No description
1,073,795 commits 117 branches 5,799 tags 5.6 GiB
  • C 96.9%
  • Assembly 0.9%
  • Rust 0.6%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Balbir Singh 9a3f2d0829 x86/kaslr: Reduce KASLR entropy on most x86 systems 
[ Upstream commit 7ffb791423 ]

When CONFIG_PCI_P2PDMA=y (which is basically enabled on all
large x86 distros), it maps the PFN's via a ZONE_DEVICE
mapping using devm_memremap_pages(). The mapped virtual
address range corresponds to the pci_resource_start()
of the BAR address and size corresponding to the BAR length.

When KASLR is enabled, the direct map range of the kernel is
reduced to the size of physical memory plus additional padding.
If the BAR address is beyond this limit, PCI peer to peer DMA
mappings fail.

Fix this by not shrinking the size of the direct map when
CONFIG_PCI_P2PDMA=y.

This reduces the total available entropy, but it's better than
the current work around of having to disable KASLR completely.

[ mingo: Clarified the changelog to point out the broad impact ... ]

Signed-off-by: Balbir Singh <balbirs@nvidia.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # drivers/pci/Kconfig
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/lkml/20250206023201.1481957-1-balbirs@nvidia.com/
Link: https://lore.kernel.org/r/20250206234234.1912585-1-balbirs@nvidia.com
--
 arch/x86/mm/kaslr.c | 10 ++++++++--
 drivers/pci/Kconfig |  6 ++++++
 2 files changed, 14 insertions(+), 2 deletions(-)
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-06-04 14:38:00 +02:00
arch x86/kaslr: Reduce KASLR entropy on most x86 systems 2025-06-04 14:38:00 +02:00
block block: fix direct io NOWAIT flag not work 2025-05-22 14:08:26 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: lzo - Fix compression buffer overrun 2025-06-04 14:37:58 +02:00
Documentation x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2 2025-06-04 14:37:59 +02:00
drivers x86/kaslr: Reduce KASLR entropy on most x86 systems 2025-06-04 14:38:00 +02:00
fs orangefs: Do not truncate file size 2025-06-04 14:37:58 +02:00
include crypto: lzo - Fix compression buffer overrun 2025-06-04 14:37:58 +02:00
init sched/isolation: Make CONFIG_CPU_ISOLATION depend on CONFIG_SMP 2025-05-02 07:44:36 +02:00
io_uring io_uring: fix possible deadlock in io_register_iowq_max_workers() 2024-11-17 15:06:25 +01:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel timer_list: Don't use %pK through printk() 2025-06-04 14:37:57 +02:00
lib crypto: lzo - Fix compression buffer overrun 2025-06-04 14:37:58 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm: fix apply_to_existing_page_range() 2025-05-02 07:44:24 +02:00
net ipv4: fib: Move fib_valid_key_len() to rtm_to_fib_config(). 2025-06-04 14:37:59 +02:00
samples samples/bpf: Fix compilation failure for samples/bpf on LoongArch Fedora 2025-06-04 14:37:54 +02:00
scripts kbuild: fix argument parsing in scripts/config 2025-06-04 14:37:57 +02:00
security landlock: Add the errata interface 2025-05-02 07:44:20 +02:00
sound ASoC: qcom: sm8250: explicitly set format in sm8250_be_hw_params_fixup() 2025-06-04 14:37:58 +02:00
tools libbpf: Fix out-of-bound read 2025-06-04 14:38:00 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-10-22 15:40:41 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS trace: Relocate event helper files 2024-04-10 16:19:24 +02:00
Makefile Linux 5.15.184 2025-05-22 14:08:28 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.