linux_dsm_epyc7002/arch/powerpc/kernel
Gustavo Romero a8318c13e7 powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts
When in userspace and MSR FP=0 the hardware FP state is unrelated to
the current process. This is extended for transactions where if tbegin
is run with FP=0, the hardware checkpoint FP state will also be
unrelated to the current process. Due to this, we need to ensure this
hardware checkpoint is updated with the correct state before we enable
FP for this process.

Unfortunately we get this wrong when returning to a process from a
hardware interrupt. A process that starts a transaction with FP=0 can
take an interrupt. When the kernel returns back to that process, we
change to FP=1 but with hardware checkpoint FP state not updated. If
this transaction is then rolled back, the FP registers now contain the
wrong state.

The process looks like this:
   Userspace:                      Kernel

               Start userspace
                with MSR FP=0 TM=1
                  < -----
   ...
   tbegin
   bne
               Hardware interrupt
                   ---- >
                                    <do_IRQ...>
                                    ....
                                    ret_from_except
                                      restore_math()
				        /* sees FP=0 */
                                        restore_fp()
                                          tm_active_with_fp()
					    /* sees FP=1 (Incorrect) */
                                          load_fp_state()
                                        FP = 0 -> 1
                  < -----
               Return to userspace
                 with MSR TM=1 FP=1
                 with junk in the FP TM checkpoint
   TM rollback
   reads FP junk

When returning from the hardware exception, tm_active_with_fp() is
incorrectly making restore_fp() call load_fp_state() which is setting
FP=1.

The fix is to remove tm_active_with_fp().

tm_active_with_fp() is attempting to handle the case where FP state
has been changed inside a transaction. In this case the checkpointed
and transactional FP state is different and hence we must restore the
FP state (ie. we can't do lazy FP restore inside a transaction that's
used FP). It's safe to remove tm_active_with_fp() as this case is
handled by restore_tm_state(). restore_tm_state() detects if FP has
been using inside a transaction and will set load_fp and call
restore_math() to ensure the FP state (checkpoint and transaction) is
restored.

This is a data integrity problem for the current process as the FP
registers are corrupted. It's also a security problem as the FP
registers from one process may be leaked to another.

Similarly for VMX.

A simple testcase to replicate this will be posted to
tools/testing/selftests/powerpc/tm/tm-poison.c

This fixes CVE-2019-15031.

Fixes: a7771176b4 ("powerpc: Don't enable FP/Altivec if not checkpointed")
Cc: stable@vger.kernel.org # 4.15+
Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190904045529.23002-2-gromero@linux.vnet.ibm.com
2019-09-04 22:31:13 +10:00
..
syscalls powerpc: Wire up clone3 syscall 2019-07-29 09:34:27 +10:00
trace powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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.gitignore
align.c powerpc/spe: Mark expected switch fall-throughs 2019-07-31 00:19:34 +10:00
asm-offsets.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
audit.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
btext.c powerpc: Rework btext_find_display to use of_stdout and device_type helpers 2018-11-26 22:33:37 +11:00
cacheinfo.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
cacheinfo.h powerpc/cacheinfo: add cacheinfo_teardown, cacheinfo_rebuild 2019-06-15 16:52:06 +10:00
compat_audit.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpu_setup_6xx.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
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dawr.c powerpc: Fix compile issue with force DAWR 2019-07-03 15:19:35 +10:00
dbell.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dma-common.c powerpc/dma: Fix invalid DMA mmap behavior 2019-07-19 21:29:49 +10:00
dma-iommu.c powerpc/pseries/dma: Allow SWIOTLB 2019-07-03 15:19:35 +10:00
dma-mask.c dma-mapping, powerpc: simplify the arch dma_set_mask override 2019-02-18 22:41:03 +11:00
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early_32.c powerpc/32: use memset() instead of memset_io() to zero BSS 2019-05-03 01:20:26 +10:00
eeh_cache.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
eeh_dev.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
eeh_driver.c powerpc/eeh: Improve recovery of passed-through devices 2019-02-05 11:55:44 +11:00
eeh_event.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
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eeh_sysfs.c powerpc/eeh: Add include_passed to eeh_pe_state_clear() 2019-02-05 11:55:43 +11:00
eeh.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
entry_32.S powerpc: Wire up clone3 syscall 2019-07-29 09:34:27 +10:00
entry_64.S powerpc: Wire up clone3 syscall 2019-07-29 09:34:27 +10:00
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exceptions-64s.S docs: powerpc: convert docs to ReST and rename to *.rst 2019-07-17 06:57:51 -03:00
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fsl_booke_entry_mapping.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
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head_32.h powerpc/32: implement fast entry for syscalls on non BOOKE 2019-05-03 01:20:27 +10:00
head_32.S powerpc fixes for 5.2 #5 2019-06-22 09:09:42 -07:00
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head_64.S powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
head_booke.h powerpc/32: fix build failure on book3e with KVM 2019-06-16 00:03:38 +10:00
head_fsl_booke.S powerpc fixes for 5.2 #5 2019-06-22 09:09:42 -07:00
hw_breakpoint.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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iomap.c powerpc: iomap.c: introduce io{read|write}64_{lo_hi|hi_lo} 2018-04-05 14:59:26 +10:00
iommu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156 2019-05-30 11:26:35 -07:00
irq.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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kgdb.c powerpc: Activate CONFIG_THREAD_INFO_IN_TASK 2019-02-23 22:31:40 +11:00
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legacy_serial.c powerpc: Use of_node_name_eq for node name comparisons 2018-12-22 21:29:50 +11:00
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Makefile powerpc/dma: Fix invalid DMA mmap behavior 2019-07-19 21:29:49 +10:00
mce_power.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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module_64.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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module.lds powerpc/modules: Fix alignment of .toc section in kernel modules 2017-12-11 13:03:35 +11:00
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pci_of_scan.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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process.c powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts 2019-09-04 22:31:13 +10:00
prom_init_check.sh powerpc fixes for 5.2 #4 2019-06-15 07:29:32 -10:00
prom_init.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
prom_parse.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
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ptrace32.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
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rtas-proc.c powerpc updates for 4.18 2018-06-07 10:23:33 -07:00
rtas-rtc.c powerpc: use time64_t in read_persistent_clock 2018-06-03 20:43:33 +10:00
rtas.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
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security.c powerpc updates for 5.2 2019-05-10 05:29:27 -07:00
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signal_32.c powerpc/tm: Fix oops on sigreturn on systems without TM 2019-07-22 13:05:23 +10:00
signal_64.c powerpc/tm: Fix oops on sigreturn on systems without TM 2019-07-22 13:05:23 +10:00
signal.c Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
signal.h powerpc/syscalls: signal_{32, 64} - switch to SYSCALL_DEFINE 2018-05-10 23:25:13 +10:00
smp-tbsync.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
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stacktrace.c powerpc: Remove export of save_stack_trace_tsk_reliable() 2019-03-02 14:43:05 +11:00
suspend.c PM: hibernate: powerpc: Expose pfn_is_nosave() prototype 2019-06-14 10:48:56 +02:00
swsusp_32.S powerpc/32s: fix suspend/resume when IBATs 4-7 are used 2019-06-19 20:05:07 +10:00
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swsusp_booke.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
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tau_6xx.c powerpc/tau: Make some function static 2018-05-25 12:04:44 +10:00
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tm.S powerpc/tm: update comment about interrupt re-entrancy 2019-07-02 21:39:49 +10:00
traps.c Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-07-08 21:48:15 -07:00
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vecemu.c powerpc: Add a missing include header 2018-05-25 12:04:46 +10:00
vector.S powerpc/64: Don't trace code that runs with the soft irq mask unreconciled 2019-05-03 01:58:11 +10:00
vmlinux.lds.S powerpc/kconfig: define CONFIG_DATA_SHIFT and CONFIG_ETEXT_SHIFT 2019-02-23 21:04:32 +11:00
watchdog.c powerpc/watchdog: Use hrtimers for per-CPU heartbeat 2019-04-30 11:31:02 +10:00