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Michael Ellerman c5c2a80368 powerpc/idle: Don't corrupt back chain when going idle 
commit 496c5fe25c upstream.

In isa206_idle_insn_mayloss() we store various registers into the stack
red zone, which is allowed.

However inside the IDLE_STATE_ENTER_SEQ_NORET macro we save r2 again,
to 0(r1), which corrupts the stack back chain.

We used to do the same in isa206_idle_insn_mayloss() itself, but we
fixed that in 73287caa92 ("powerpc64/idle: Fix SP offsets when saving
GPRs"), however we missed that the macro also corrupts the back chain.

Corrupting the back chain is bad for debuggability but doesn't
necessarily cause a bug.

However we recently changed the stack handling in some KVM code, and it
now relies on the stack back chain being valid when it returns. The
corruption causes that code to return with r1 pointing somewhere in
kernel data, at some point LR is restored from the stack and we branch
to NULL or somewhere else invalid.

Only affects Power8 hosts running KVM guests, with dynamic_mt_modes
enabled (which it is by default).

The fixes tag below points to the commit that changed the KVM stack
handling, exposing this bug. The actual corruption of the back chain has
always existed since 948cf67c47 ("powerpc: Add NAP mode support on
Power7 in HV mode").

Fixes: 9b4416c509 ("KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211020094826.3222052-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-27 09:56:53 +02:00
arch powerpc/idle: Don't corrupt back chain when going idle 2021-10-27 09:56:53 +02:00
block block: decode QUEUE_FLAG_HCTX_ACTIVE in debugfs output 2021-10-27 09:56:46 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: sm2 - fix a memory leak in sm2 2021-07-14 16:56:06 +02:00
Documentation dt-bindings: drm/bridge: ti-sn65dsi86: Fix reg value 2021-10-13 10:04:27 +02:00
drivers net: dsa: mt7530: correct ds->num_ports 2021-10-27 09:56:52 +02:00
fs vfs: check fd has read access in kernel_read_file_from_fd() 2021-10-27 09:56:51 +02:00
include elfcore: correct reference to CONFIG_UML 2021-10-27 09:56:51 +02:00
init sched/core: Initialize the idle task with preemption disabled 2021-07-14 16:55:50 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel audit: fix possible null-pointer dereference in audit_filter_rules 2021-10-27 09:56:52 +02:00
lib treewide: Change list_sort to use const pointers 2021-09-30 10:11:04 +02:00
LICENSES
mm mm: don't allow oversized kvmalloc() calls 2021-10-06 15:56:03 +02:00
net can: j1939: j1939_xtp_rx_rts_session_new(): abort TP less than 9 bytes 2021-10-27 09:56:51 +02:00
samples samples: bpf: Fix tracex7 error raised on the missing argument 2021-09-18 13:40:23 +02:00
scripts nds32/ftrace: Fix Error: invalid operands (*UND* and *UND* sections) for `^' 2021-10-20 11:44:58 +02:00
security Smack: Fix wrong semantics in smk_access_entry() 2021-09-18 13:40:18 +02:00
sound ASoC: DAPM: Fix missing kctl change notifications 2021-10-27 09:56:52 +02:00
tools ipv6: When forwarding count rx stats on the orig netdev 2021-10-27 09:56:48 +02:00
usr
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:40:58 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
Kconfig
MAINTAINERS f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.75 2021-10-20 11:45:06 +02:00
README

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.