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[PATCH 4.1 017/159] arm64: flush FP/SIMD state correctly after execve()

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4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

commit 674c242c9323d3c293fc4f9a3a3a619fe3063290 upstream.

When a task calls execve(), its FP/SIMD state is flushed so that
none of the original program state is observeable by the incoming
program.

However, since this flushing consists of setting the in-memory copy
of the FP/SIMD state to all zeroes, the CPU field is set to CPU 0 as
well, which indicates to the lazy FP/SIMD preserve/restore code that
the FP/SIMD state does not need to be reread from memory if the task
is scheduled again on CPU 0 without any other tasks having entered
userland (or used the FP/SIMD in kernel mode) on the same CPU in the
mean time. If this happens, the FP/SIMD state of the old program will
still be present in the registers when the new program starts.

So set the CPU field to the invalid value of NR_CPUS when performing
the flush, by calling fpsimd_flush_task_state().

Reported-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
Reported-by: Janet Liu <janet.liu@spreadtrum.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/kernel/fpsimd.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -157,6 +157,7 @@ void fpsimd_thread_switch(struct task_st
 void fpsimd_flush_thread(void)
 {
 	memset(&current->thread.fpsimd_state, 0, sizeof(struct fpsimd_state));
+	fpsimd_flush_task_state(current);
 	set_thread_flag(TIF_FOREIGN_FPSTATE);
 }
 


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[PATCH 4.1 000/159] 4.1.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 087/159] md/raid10: always set reshape_safe when initializing reshape_position. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 090/159] iommu/io-pgtable-arm: Unmap and free table when overwriting with block Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 042/159] powerpc/mm: Recompute hash value after a failed update Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 040/159] crypto: vmx - Adding enable_kernel_vsx() to access VSX instructions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 044/159] Add radeon suspend/resume quirk for HP Compaq dc5750. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 078/159] parisc: Filter out spurious interrupts in PA-RISC irq handler Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 037/159] powerpc/mm: Fix pte_pagesize_index() crash on 4K w/64K hash Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 062/159] NFS41/flexfiles: update inode after write finishes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 038/159] powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 021/159] arm64: head.S: initialise mdcr_el2 in el2_setup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 015/159] Revert "ext4: remove block_device_ejected" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 066/159] NFSv4.1: Fix a protocol issue with CLOSE stateids Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 031/159] ALSA: hda - Add some FIXUP quirks for white noise on Dell laptop. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 029/159] ALSA: hda - Enable headphone jack detect on old Fujitsu laptops Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 065/159] NFSv4.1/flexfiles: Fix a protocol error in layoutreturn Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 020/159] arm64: compat: fix vfp save/restore across signal handlers in big-endian Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 064/159] NFS41/flexfiles: zero out DS write wcc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 039/159] powerpc: Uncomment and make enable_kernel_vsx() routine available Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 067/159] Revert "NFSv4: Remove incorrect check in can_open_delegated()" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 035/159] powerpc/eeh: Probe after unbalanced kref check Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 030/159] ALSA: hda - Use ALC880_FIXUP_FUJITSU for FSC Amilo M1437 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 089/159] iommu/fsl: Really fix init section(s) content Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 041/159] powerpc/boot: Specify ABI v2 when building an LE boot wrapper Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 012/159] cxl: Remove racy attempt to force EEH invocation in reset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 063/159] NFSv4: Force a post-op attribute update when holding a delegation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 036/159] powerpc/eeh: Fix fenced PHB caused by eeh_slot_error_detail() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-26 23:50 +0200
  [PATCH 4.1 011/159] mac80211: enable assoc check for mesh interfaces Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 005/159] rtlwifi: rtl8192cu: Add new device ID Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 013/159] cxl: Fix unbalanced pci_dev_get in cxl_probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 008/159] tg3: Fix temperature reporting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 010/159] MIPS: math-emu: Emulate missing BC1{EQ,NE}Z instructions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 007/159] igb: Fix oops caused by missing queue pairing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 001/159] NFC: st21nfca: fix use of uninitialized variables in error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 018/159] of/fdt: make memblock maximum physical address arch configurable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 014/159] ext4: dont manipulate recovery flag when freezing no-journal fs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 006/159] rtlwifi: rtl8821ae: Fix an expression that is always false Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 004/159] unshare: Unsharing a thread does not require unsharing a vm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 017/159] arm64: flush FP/SIMD state correctly after execve() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 003/159] blk-mq: fix buffer overflow when reading sysfs file of pending Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  [PATCH 4.1 002/159] nfc: nci: hci: Add check on skb nci_hci_send_cmd parameter Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 00:00 +0200
  Re: [PATCH 4.1 000/159] 4.1.9-stable review (build error) Guenter Roeck <linux@roeck-us.net> - 2015-09-27 02:40 +0200
    [PATCH] cxl: Don't remove AFUs/vPHBs in cxl_reset Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2015-09-27 08:50 +0200
      Re: [PATCH] cxl: Don't remove AFUs/vPHBs in cxl_reset Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 17:40 +0200
      Re: [PATCH] cxl: Don't remove AFUs/vPHBs in cxl_reset Daniel Axtens <dja@axtens.net> - 2015-09-29 07:30 +0200
  Re: [PATCH 4.1 000/159] 4.1.9-stable review Guenter Roeck <linux@roeck-us.net> - 2015-09-27 21:20 +0200
    Re: [PATCH 4.1 000/159] 4.1.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-27 21:40 +0200
  Re: [PATCH 4.1 000/159] 4.1.9-stable review Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2015-09-28 07:10 +0200
    Re: [PATCH 4.1 000/159] 4.1.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-28 16:30 +0200
  Re: [PATCH 4.1 000/159] 4.1.9-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2015-09-28 19:40 +0200
    Re: [PATCH 4.1 000/159] 4.1.9-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-09-28 23:40 +0200
  Re: [PATCH 4.1 000/159] 4.1.9-stable review "Andre Tomt (LKML)" <lkml@tomt.net> - 2015-09-29 03:00 +0200

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