[PATCH 3.2 39/94] ARM: fix PTRACE_SETVFPREGS on SMP systems

From	Ben Hutchings <ben@decadent.org.uk>
Newsgroups	linux.kernel
Subject	[PATCH 3.2 39/94] ARM: fix PTRACE_SETVFPREGS on SMP systems
Date	2016-08-14 20:00 +0200
Message-ID	<s67Rv-2Hd-5@gated-at.bofh.it> (permalink)
References	<s5LnX-4sk-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.2.82-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Russell King <rmk+kernel@armlinux.org.uk>

commit e2dfb4b880146bfd4b6aa8e138c0205407cebbaf upstream.

PTRACE_SETVFPREGS fails to properly mark the VFP register set to be
reloaded, because it undoes one of the effects of vfp_flush_hwstate().

Specifically vfp_flush_hwstate() sets thread->vfpstate.hard.cpu to
an invalid CPU number, but vfp_set() overwrites this with the original
CPU number, thereby rendering the hardware state as apparently "valid",
even though the software state is more recent.

Fix this by reverting the previous change.

Fixes: 8130b9d7b9d8 ("ARM: 7308/1: vfp: flush thread hwstate before copying ptrace registers")
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Simon Marchi <simon.marchi@ericsson.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 arch/arm/kernel/ptrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -726,8 +726,8 @@ static int vfp_set(struct task_struct *t
 	if (ret)
 		return ret;
 
-	vfp_flush_hwstate(thread);
 	thread->vfpstate.hard = new_vfp;
+	vfp_flush_hwstate(thread);
 
 	return 0;
 }

Thread

[PATCH 3.2 00/94] 3.2.82-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 13:50 +0200
  [PATCH 3.2 26/94] fs/cifs: correctly to anonymous authentication  for the LANMAN authentication Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 13:50 +0200
  [PATCH 3.2 23/94] x86/PCI: Mark Broadwell-EP Home Agent 1 as  having non-compliant BARs Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 13:50 +0200
  [PATCH 3.2 93/94] tcp: make challenge acks less predictable Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 13:50 +0200
  [PATCH 3.2 62/94] UBIFS: Implement ->migratepage() Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 42/94] x86, build: copy ldlinux.c32 to image.iso Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 54/94] kvm: Fix irq route entries exceeding  KVM_MAX_IRQ_ROUTES Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 13/94] USB: serial: option: add even more ZTE device ids Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 35/94] Input: xpad - prevent spurious input from wired  Xbox 360 controllers Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 43/94] fix d_walk()/non-delayed __d_free() race Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 18/94] powerpc/mm/hash64: Factor out hash preload  psize check Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:00 +0200
  [PATCH 3.2 86/94] proc: prevent stacking filesystems on top Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 34/94] RDMA/cxgb3: device driver frees DMA memory with  different size Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 22/94] net/mlx4_core: Fix access to uninitialized index Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 82/94] xenbus: don't BUG() on user mode induced condition Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 69/94] ALSA: dummy: Fix a use-after-free at closing Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 74/94] NFS: Fix another OPEN_DOWNGRADE bug Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 73/94] ALSA: echoaudio: Fix memory allocation Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 61/94] mm: Export migrate_page_move_mapping and  migrate_page_copy Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  [PATCH 3.2 02/94] ath5k: Change led pin configuration for compaq  c700 laptop Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 14:10 +0200
  Re: [PATCH 3.2 00/94] 3.2.82-rc1 review Guenter Roeck <linux@roeck-us.net> - 2016-08-14 17:10 +0200
  [PATCH 3.2 39/94] ARM: fix PTRACE_SETVFPREGS on SMP systems Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 85/94] fs: limit filesystem stacking depth Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 11/94] tty: vt, return error when con_startup fails Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 91/94] tipc: fix an infoleak in tipc_nl_compat_link_dump Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 15/94] MIPS: Adjust set_pte() SMP fix to handle  R10000_LLSC_WAR Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 60/94] ubi: Make recover_peb power cut aware Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 03/94] crypto: s5p-sss - Fix missed interrupts when  working with 8 kB blocks Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 64/94] xen/pciback: Fix conf_space read/write overlap  check. Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 25/94] fs/cifs: correctly to anonymous authentication  via NTLMSSP Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:00 +0200
  [PATCH 3.2 37/94] Input: pwm-beeper - fix - scheduling while atomic Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 21/94] mmc: mmc: Fix partition switch timeout for some  eMMCs Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 88/94] ALSA: timer: Fix leak in SNDRV_TIMER_IOCTL_PARAMS Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 01/94] regmap: cache: Fix typo in cache_bypass  parameter description Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 63/94] can: fix oops caused by wrong rtnl dellink usage Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 77/94] x86/amd_nb: Fix boot crash on non-AMD systems Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 79/94] bonding: prevent out of bound accesses Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 06/94] crypto: s5p-sss - fix incorrect usage of  scatterlists api Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 59/94] can: at91_can: RX queue could get stuck at high  bus load Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 70/94] fs/nilfs2: fix potential underflow in call to  crc32_le Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 71/94] staging: iio: accel: fix error check Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 84/94] cifs: dynamic allocation of ntlmssp blob Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 52/94] kernel/sysrq, watchdog, sched/core: Reset  watchdog on all CPUs while processing sysrq-w Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 40/94] KVM: x86: fix OOPS after invalid KVM_SET_DEBUGREGS Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 53/94] base: make module_create_drivers_dir race-free Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:10 +0200
  [PATCH 3.2 87/94] USB: usbfs: fix potential infoleak in devio Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:20 +0200
  [PATCH 3.2 48/94] staging:iio: trigger fixes for repeat request  of same trigger and allocation failure Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:20 +0200
  [PATCH 3.2 09/94] ext4: fix hang when processing corrupted  orphaned inode list Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:20 +0200
  [PATCH 3.2 75/94] batman-adv: Fix use-after-free/double-free of  tt_req_node Ben Hutchings <ben@decadent.org.uk> - 2016-08-14 20:20 +0200

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