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Filename Latest commit message Latest commit date
Sean Christopherson 5cce2ed69b KVM: Explicitly verify target vCPU is online in kvm_get_vcpu()
commit 1e7381f3617d14b3c11da80ff5f8a93ab14cfc46 upstream.

Explicitly verify the target vCPU is fully online _prior_ to clamping the
index in kvm_get_vcpu().  If the index is "bad", the nospec clamping will
generate '0', i.e. KVM will return vCPU0 instead of NULL.

In practice, the bug is unlikely to cause problems, as it will only come
into play if userspace or the guest is buggy or misbehaving, e.g. KVM may
send interrupts to vCPU0 instead of dropping them on the floor.

However, returning vCPU0 when it shouldn't exist per online_vcpus is
problematic now that KVM uses an xarray for the vCPUs array, as KVM needs
to insert into the xarray before publishing the vCPU to userspace (see
commit c5b077549136 ("KVM: Convert the kvm->vcpus array to a xarray")),
i.e. before vCPU creation is guaranteed to succeed.

As a result, incorrectly providing access to vCPU0 will trigger a
use-after-free if vCPU0 is dereferenced and kvm_vm_ioctl_create_vcpu()
bails out of vCPU creation due to an error and frees vCPU0.  Commit
afb2acb2e3a3 ("KVM: Fix vcpu_array[0] races") papered over that issue, but
in doing so introduced an unsolvable teardown conundrum.  Preventing
accesses to vCPU0 before it's fully online will allow reverting commit
afb2acb2e3a3, without re-introducing the vcpu_array[0] UAF race.

Fixes: 1d487e9bf8 ("KVM: fix spectrev1 gadgets")
Cc: stable@vger.kernel.org
Cc: Will Deacon <will@kernel.org>
Cc: Michal Luczaj <mhal@rbox.co>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241009150455.1057573-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-03-13 12:43:07 +01:00
arch arm64: dts: rockchip: increase gmac rx_delay on rk3399-puma 2025-03-13 12:43:07 +01:00
block partitions: ldm: remove the initial kernel-doc notation 2025-03-13 12:42:52 +01:00
certs
crypto crypto: pcrypt - Call crypto layer directly when padata_do_parallel() return -EBUSY 2024-12-14 19:44:23 +01:00
Documentation dt-bindings: mmc: controller: clarify the address-cells description 2025-03-13 12:42:53 +01:00
drivers leds: lp8860: Write full EEPROM, not only half of it 2025-03-13 12:43:06 +01:00
fs binfmt_flat: Fix integer overflow bug on 32 bit systems 2025-03-13 12:43:07 +01:00
include KVM: Explicitly verify target vCPU is online in kvm_get_vcpu() 2025-03-13 12:43:07 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:44:21 +01:00
ipc
kernel tasklet: Introduce new initialization API 2025-03-13 12:43:04 +01:00
lib lib: string_helpers: silence snprintf() output truncation warning 2024-12-14 19:44:39 +01:00
LICENSES
mm mm: vmscan: account for free pages to prevent infinite Loop in throttle_direct_reclaim() 2025-01-09 13:23:37 +01:00
net netem: Update sch->q.qlen before qdisc_tree_reduce_backlog() 2025-03-13 12:43:06 +01:00
samples samples/bpf: Fix a resource leak 2024-12-14 19:44:50 +01:00
scripts genksyms: fix memory leak when the same symbol is read from *.symref file 2025-03-13 12:43:00 +01:00
security tomoyo: don't emit warning in tomoyo_write_control() 2025-03-13 12:43:03 +01:00
sound ASoC: sun4i-spdif: Add clock multiplier settings 2025-03-13 12:42:55 +01:00
tools udp: gso: do not drop small packets when PMTU reduces 2025-03-13 12:43:06 +01:00
usr
virt KVM: arm64: Ignore PMCNTENSET_EL0 while checking for overflow status 2024-12-19 18:05:04 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore Remove *.orig pattern from .gitignore 2024-11-08 16:20:33 +01:00
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile kbuild: userprogs: use correct lld when linking through clang 2025-03-13 12:43:04 +01:00
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.