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linux/arch/x86/kernel
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Reinette Chatre c3eeb1ffc6 x86/resctrl: Fix uninitialized memory read when last CPU of domain goes offline 
Tony encountered this OOPS when the last CPU of a domain goes
offline while running a kernel built with CONFIG_NO_HZ_FULL:

    BUG: kernel NULL pointer dereference, address: 0000000000000000
    #PF: supervisor read access in kernel mode
    #PF: error_code(0x0000) - not-present page
    PGD 0
    Oops: 0000 [#1] PREEMPT SMP NOPTI
    ...
    RIP: 0010:__find_nth_andnot_bit+0x66/0x110
    ...
    Call Trace:
     <TASK>
     ? __die()
     ? page_fault_oops()
     ? exc_page_fault()
     ? asm_exc_page_fault()
     cpumask_any_housekeeping()
     mbm_setup_overflow_handler()
     resctrl_offline_cpu()
     resctrl_arch_offline_cpu()
     cpuhp_invoke_callback()
     cpuhp_thread_fun()
     smpboot_thread_fn()
     kthread()
     ret_from_fork()
     ret_from_fork_asm()
     </TASK>

The NULL pointer dereference is encountered while searching for another
online CPU in the domain (of which there are none) that can be used to
run the MBM overflow handler.

Because the kernel is configured with CONFIG_NO_HZ_FULL the search for
another CPU (in its effort to prefer those CPUs that aren't marked
nohz_full) consults the mask representing the nohz_full CPUs,
tick_nohz_full_mask. On a kernel with CONFIG_CPUMASK_OFFSTACK=y
tick_nohz_full_mask is not allocated unless the kernel is booted with
the "nohz_full=" parameter and because of that any access to
tick_nohz_full_mask needs to be guarded with tick_nohz_full_enabled().

Replace the IS_ENABLED(CONFIG_NO_HZ_FULL) with tick_nohz_full_enabled().
The latter ensures tick_nohz_full_mask can be accessed safely and can be
used whether kernel is built with CONFIG_NO_HZ_FULL enabled or not.

[ Use Ingo's suggestion that combines the two NO_HZ checks into one. ]

Fixes: a4846aaf39 ("x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow")
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/ff8dfc8d3dcb04b236d523d1e0de13d2ef585223.1711993956.git.reinette.chatre@intel.com
Closes: https://lore.kernel.org/lkml/ZgIFT5gZgIQ9A9G7@agluck-desk3/
2024-04-03 09:30:01 +02:00
..
acpi ACPI updates for 6.9-rc1 2024-03-13 11:54:05 -07:00
apic Rework of APIC enumeration and topology evaluation: 2024-03-11 15:45:55 -07:00
cpu x86/resctrl: Fix uninitialized memory read when last CPU of domain goes offline 2024-04-03 09:30:01 +02:00
fpu x86/fpu: Keep xfd_state in sync with MSR_IA32_XFD 2024-03-24 04:03:54 +01:00
kprobes kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address 2024-03-22 11:40:56 +01:00
.gitignore
alternative.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
amd_gart_64.c arch/x86: Fix typos 2024-01-03 11:46:22 +01:00
amd_nb.c x86/cpu/amd: Provide a separate accessor for Node ID 2024-02-15 22:07:37 +01:00
aperture_64.c x86/pci: Use PCI_HEADER_TYPE_* instead of literals 2023-12-01 15:00:43 -06:00
apm_32.c x86/apm_32: Remove dead function apm_get_battery_status() 2024-02-21 19:38:03 +01:00
asm-offsets.c x86/bugs: Rename CONFIG_CALL_DEPTH_TRACKING => CONFIG_MITIGATION_CALL_DEPTH_TRACKING 2024-01-10 10:52:28 +01:00
asm-offsets_32.c
asm-offsets_64.c
audit_64.c x86/audit: Fix -Wmissing-variable-declarations warning for ia32_xyz_class 2023-08-30 10:11:16 +02:00
bootflag.c
callthunks.c Core x86 changes for v6.9: 2024-03-11 19:53:15 -07:00
cet.c x86/ibt: Convert IBT selftest to asm 2023-08-17 17:07:09 +02:00
cfi.c cfi: Flip headers 2023-12-15 16:25:55 -08:00
check.c
cpuid.c x86/cpuid: make cpuid_class a static const structure 2023-08-05 08:31:41 +02:00
crash.c x86/build changes for v6.9: 2024-03-11 19:23:16 -07:00
crash_dump_32.c
crash_dump_64.c
devicetree.c Devicetree updates for v6.9: 2024-03-15 12:37:59 -07:00
doublefault_32.c x86: Avoid missing-prototype warnings for doublefault code 2023-05-18 11:56:18 -07:00
dumpstack.c x86/bugs: Rename CONFIG_PAGE_TABLE_ISOLATION => CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 2024-01-10 10:52:28 +01:00
dumpstack_32.c
dumpstack_64.c
e820.c x86/kexec: Do not update E820 kexec table for setup_data 2024-03-22 10:07:45 +01:00
early-quirks.c x86/pci: Use PCI_HEADER_TYPE_* instead of literals 2023-12-01 15:00:43 -06:00
early_printk.c
ebda.c
eisa.c x86/sev: Skip ROM range scans and validation for SEV-SNP guests 2024-03-26 15:22:35 +01:00
espfix_64.c x86/fred: No ESPFIX needed when FRED is enabled 2024-01-31 22:01:51 +01:00
fred.c x86/fred: Add FRED initialization functions 2024-01-31 22:03:32 +01:00
ftrace.c x86/bugs: Rename CONFIG_SLS => CONFIG_MITIGATION_SLS 2024-01-10 10:52:28 +01:00
ftrace_32.S x86/headers: Replace #include <asm/export.h> with #include <linux/export.h> 2023-10-03 10:38:07 +02:00
ftrace_64.S x86/headers: Replace #include <asm/export.h> with #include <linux/export.h> 2023-10-03 10:38:07 +02:00
head32.c x86/microcode/32: Move early loading after paging enable 2023-10-18 22:15:01 +02:00
head64.c x86/boot/64: Move 5-level paging global variable assignments back 2024-03-24 05:00:36 +01:00
head_32.S x86/bugs: Rename CONFIG_PAGE_TABLE_ISOLATION => CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 2024-01-10 10:52:28 +01:00
head_64.S Merge branch 'linus' into x86/boot, to resolve conflict 2024-03-12 09:55:57 +01:00
hpet.c x86/apic/msi: Use DOMAIN_BUS_GENERIC_MSI for HPET/IO-APIC domain search 2024-02-25 18:53:08 +01:00
hw_breakpoint.c
i8237.c
i8253.c
i8259.c x86/i8259: Skip probing when ACPI/MADT advertises PCAT compatibility 2023-10-27 20:36:49 +02:00
ibt_selftest.S x86/ibt: Convert IBT selftest to asm 2023-08-17 17:07:09 +02:00
idt.c S390: 2024-03-15 13:03:13 -07:00
io_delay.c
ioport.c
irq.c x86: replace CONFIG_HAVE_KVM with IS_ENABLED(CONFIG_KVM) 2024-02-08 08:45:35 -05:00
irq_32.c
irq_64.c
irq_work.c x86/apic: Wrap IPI calls into helper functions 2023-08-09 12:00:55 -07:00
irqflags.S x86/headers: Replace #include <asm/export.h> with #include <linux/export.h> 2023-10-03 10:38:07 +02:00
irqinit.c x86/fred: Invoke FRED initialization code to enable FRED 2024-01-31 22:03:36 +01:00
itmt.c arch/x86: Remove now superfluous sentinel elem from ctl_table arrays 2023-10-10 15:22:02 -07:00
jailhouse.c x86/jailhouse: Use new APIC registration function 2024-02-15 22:07:42 +01:00
jump_label.c
kdebugfs.c
kexec-bzimage64.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
kgdb.c x86/kgdb: Fix a kerneldoc warning when build with W=1 2023-09-24 11:00:13 +02:00
ksysfs.c
kvm.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
kvmclock.c kvmclock: Unexport kvmclock clocksource 2024-02-07 17:05:21 +01:00
ldt.c x86/bugs: Rename CONFIG_PAGE_TABLE_ISOLATION => CONFIG_MITIGATION_PAGE_TABLE_ISOLATION 2024-01-10 10:52:28 +01:00
machine_kexec_32.c
machine_kexec_64.c x86, crash: wrap crash dumping code into crash related ifdefs 2024-02-23 17:48:23 -08:00
Makefile - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
mmconf-fam10h_64.c
module.c x86/paravirt: Switch mixed paravirt/alternative calls to alternatives 2023-12-10 23:33:09 +01:00
mpparse.c x86/mpparse: Register APIC address only once 2024-03-23 12:41:48 +01:00
msr.c x86/MSR: make msr_class a static const structure 2023-08-05 08:31:42 +02:00
nmi.c x86/nmi: Upgrade NMI backtrace stall checks & messages 2024-03-26 10:07:59 +01:00
nmi_selftest.c x86/apic: Wrap IPI calls into helper functions 2023-08-09 12:00:55 -07:00
paravirt-spinlocks.c
paravirt.c x86/paravirt: Remove no longer needed paravirt patching code 2023-12-10 23:34:37 +01:00
pci-dma.c x86: always initialize xen-swiotlb when xen-pcifront is enabling 2023-07-31 17:54:27 +02:00
pcspeaker.c
perf_regs.c
platform-quirks.c x86/quirks: Include linux/pnp.h for arch_pnpbios_disabled() 2023-05-18 11:56:18 -07:00
pmem.c
probe_roms.c x86/sev: Skip ROM range scans and validation for SEV-SNP guests 2024-03-26 15:22:35 +01:00
process.c Core x86 changes for v6.9: 2024-03-11 19:53:15 -07:00
process.h
process_32.c x86/fpu: Clean up FPU switching in the middle of task switching 2023-10-20 11:24:22 +02:00
process_64.c Core x86 changes for v6.9: 2024-03-11 19:53:15 -07:00
ptrace.c x86: Add PTRACE interface for shadow stack 2023-08-02 15:01:51 -07:00
pvclock.c locking/atomic: treewide: use raw_atomic*_<op>() 2023-06-05 09:57:20 +02:00
quirks.c
reboot.c x86, crash: wrap crash dumping code into crash related ifdefs 2024-02-23 17:48:23 -08:00
reboot_fixups_32.c
relocate_kernel_32.S
relocate_kernel_64.S
resource.c
rethook.c
rtc.c rtc: Extend timeout for waiting for UIP to clear to 1s 2023-12-17 22:33:55 +01:00
setup.c x86/sev: Skip ROM range scans and validation for SEV-SNP guests 2024-03-26 15:22:35 +01:00
setup_percpu.c x86/asm: Add DB flag to 32-bit percpu GDT entry 2023-12-20 10:57:51 +01:00
sev-shared.c Merge branch 'linus' into x86/boot, to resolve conflict 2024-03-12 09:55:57 +01:00
sev.c x86/sev: Skip ROM range scans and validation for SEV-SNP guests 2024-03-26 15:22:35 +01:00
sev_verify_cbit.S x86/boot: Use 32-bit XOR to clear registers 2024-03-01 12:47:37 +01:00
shstk.c x86/shstk: Add warning for shadow stack double unmap 2023-09-19 09:18:34 -07:00
signal.c rseq: Split out rseq.h from sched.h 2023-12-27 11:49:56 -05:00
signal_32.c x86/shstk: Add user control-protection fault handler 2023-08-02 15:01:50 -07:00
signal_64.c x86/shstk: Delay signal entry SSP write until after user accesses 2023-11-08 08:55:37 -08:00
smp.c - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames 2024-03-14 17:43:30 -07:00
smpboot.c x86/cpu: Ensure that CPU info updates are propagated on UP 2024-03-23 12:22:04 +01:00
stacktrace.c
static_call.c x86/bugs: Rename CONFIG_RETHUNK => CONFIG_MITIGATION_RETHUNK 2024-01-10 10:52:29 +01:00
step.c x86/msr: Prepare for including <linux/percpu.h> into <asm/msr.h> 2024-03-04 12:01:39 +01:00
sys_ia32.c
sys_x86_64.c x86/vdso: Move vDSO to mmap region 2024-02-27 00:23:55 +01:00
tboot.c
time.c
tls.c
tls.h
topology.c x86/topology: convert to use arch_cpu_is_hotpluggable() 2023-12-06 12:41:49 +09:00
trace.c
trace_clock.c
tracepoint.c
traps.c Core x86 changes for v6.9: 2024-03-11 19:53:15 -07:00
tsc.c treewide: Remove system_counterval_t.cs, which is never read 2024-02-07 17:05:21 +01:00
tsc_msr.c
tsc_sync.c x86/tsc: Defer marking TSC unstable to a worker 2023-10-27 20:36:57 +02:00
umip.c
unwind_frame.c
unwind_guess.c
unwind_orc.c x86/unwind/orc: Remove redundant initialization of 'mid' pointer in __orc_find() 2023-09-21 08:41:23 +02:00
uprobes.c
verify_cpu.S
vm86_32.c
vmcore_info_32.c crash: split vmcoreinfo exporting code out from crash_core.c 2024-02-23 17:48:22 -08:00
vmcore_info_64.c crash: split vmcoreinfo exporting code out from crash_core.c 2024-02-23 17:48:22 -08:00
vmlinux.lds.S Merge branch 'x86/bugs' into x86/core, to pick up pending changes before dependent patches 2024-02-14 10:49:37 +01:00
vsmp_64.c x86/apic: Remove unused phys_pkg_id() callback 2024-02-15 22:07:38 +01:00
x86_init.c x86/sev: Skip ROM range scans and validation for SEV-SNP guests 2024-03-26 15:22:35 +01:00