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[PATCH 3.12 16/72] powerpc/vdso64: Use double word compare on pointers

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From: Anton Blanchard <anton@samba.org>

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

===============

commit 5045ea37377ce8cca6890d32b127ad6770e6dce5 upstream.

__kernel_get_syscall_map() and __kernel_clock_getres() use cmpli to
check if the passed in pointer is non zero. cmpli maps to a 32 bit
compare on binutils, so we ignore the top 32 bits.

A simple test case can be created by passing in a bogus pointer with
the bottom 32 bits clear. Using a clk_id that is handled by the VDSO,
then one that is handled by the kernel shows the problem:

  printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000));
  printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000));

And we get:

  0
  -1

The bigger issue is if we pass a valid pointer with the bottom 32 bits
clear, in this case we will return success but won't write any data
to the pointer.

I stumbled across this issue because the LLVM integrated assembler
doesn't accept cmpli with 3 arguments. Fix this by converting them to
cmpldi.

Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/powerpc/kernel/vdso64/datapage.S     | 2 +-
 arch/powerpc/kernel/vdso64/gettimeofday.S | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/vdso64/datapage.S b/arch/powerpc/kernel/vdso64/datapage.S
index 79796de11737..3263ee23170d 100644
--- a/arch/powerpc/kernel/vdso64/datapage.S
+++ b/arch/powerpc/kernel/vdso64/datapage.S
@@ -57,7 +57,7 @@ V_FUNCTION_BEGIN(__kernel_get_syscall_map)
 	bl	V_LOCAL_FUNC(__get_datapage)
 	mtlr	r12
 	addi	r3,r3,CFG_SYSCALL_MAP64
-	cmpli	cr0,r4,0
+	cmpldi	cr0,r4,0
 	crclr	cr0*4+so
 	beqlr
 	li	r0,__NR_syscalls
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index a76b4af37ef2..382021324883 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -145,7 +145,7 @@ V_FUNCTION_BEGIN(__kernel_clock_getres)
 	bne	cr0,99f
 
 	li	r3,0
-	cmpli	cr0,r4,0
+	cmpldi	cr0,r4,0
 	crclr	cr0*4+so
 	beqlr
 	lis	r5,CLOCK_REALTIME_RES@h
-- 
2.10.2

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[PATCH 3.12 00/72] 3.12.67-stable review Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:10 +0100
  [PATCH 3.12 01/72] i40e: avoid NULL pointer dereference and recursive errors on early PCI error Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 03/72] scsi: ibmvfc: Fix I/O hang when port is not mapped Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 19/72] powerpc/pseries: Fix stack corruption in htpe code Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 10/72] regulator: tps65910: Work around silicon erratum SWCZ010 Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 15/72] dm: mark request_queue dead before destroying the DM device Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 16/72] powerpc/vdso64: Use double word compare on pointers Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 22/72] zfcp: close window with unblocked rport during rport gone Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 09/72] gpio: mpc8xxx: Correct irq handler function Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 23/72] zfcp: retain trace level for SCSI and HBA FSF response records Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 07/72] pstore: Fix buffer overflow while write offset equal to buffer size Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 06/72] cfq: fix starvation of asynchronous writes Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 08/72] ipc: remove use of seq_printf return value Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 17/72] powerpc/powernv: Use CPU-endian PEST in pnv_pci_dump_p7ioc_diag_data() Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
    [PATCH 3.12 20/72] zfcp: fix fc_host port_type with NPIV Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:30 +0100
  [PATCH 3.12 62/72] powerpc/eeh: Null check uses of eeh_pe_bus_get Jiri Slaby <jslaby@suse.cz> - 2016-11-07 14:40 +0100
  Re: [PATCH 3.12 00/72] 3.12.67-stable review Guenter Roeck <linux@roeck-us.net> - 2016-11-07 18:20 +0100
    Re: [PATCH 3.12 00/72] 3.12.67-stable review Jiri Slaby <jslaby@suse.cz> - 2016-11-08 16:50 +0100
      Re: [PATCH 3.12 00/72] 3.12.67-stable review Guenter Roeck <linux@roeck-us.net> - 2016-11-09 05:20 +0100
        Re: [PATCH 3.12 00/72] 3.12.67-stable review Jiri Slaby <jslaby@suse.cz> - 2016-11-10 20:00 +0100
  Re: [PATCH 3.12 00/72] 3.12.67-stable review Shuah Khan <shuah.kh@samsung.com> - 2016-11-07 19:40 +0100
    Re: [PATCH 3.12 00/72] 3.12.67-stable review Jiri Slaby <jslaby@suse.cz> - 2016-11-10 20:00 +0100

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