linux/arch
Dave Martin 247f4993a5 ARM: 7307/1: vfp: fix ptrace regset modification race
In a preemptible kernel, vfp_set() can be preempted, causing the
hardware VFP context to be switched while the thread vfp state is
being read and modified.  This leads to a race condition which can
cause the thread vfp state to become corrupted if lazy VFP context
save occurs due to preemption in between the time thread->vfpstate
is read and the time the modified state is written back.

This may occur if preemption occurs during the execution of a
ptrace() call which modifies the VFP register state of a thread.
Such instances should be very rare in most realistic scenarios --
none has been reported, so far as I am aware.  Only uniprocessor
systems should be affected, since VFP context save is not currently
lazy in SMP kernels.

The problem was introduced by my earlier patch migrating to use
regsets to implement ptrace.

This patch does a vfp_sync_hwstate() before reading
thread->vfpstate, to make sure that the thread's VFP state is not
live in the hardware registers while the registers are modified.

Thanks to Will Deacon for spotting this.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-02-02 17:37:42 +00:00
..
alpha Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
arm ARM: 7307/1: vfp: fix ptrace regset modification race 2012-02-02 17:37:42 +00:00
avr32 treewide: remove useless NORET_TYPE macro and uses 2012-01-12 20:13:03 -08:00
blackfin Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
c6x C6X: replace tick_nohz_stop/restart_sched_tick calls 2012-01-08 15:13:16 -05:00
cris lib: use generic pci_iomap on all architectures 2012-01-10 18:04:27 -08:00
frv Merge branch 'for-next' of git://git.infradead.org/users/dhowells/linux-headers 2012-01-14 18:03:30 -08:00
h8300 Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
hexagon lib: move GENERIC_IOMAP to lib/Kconfig 2011-11-24 22:21:19 +02:00
ia64 Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2012-01-18 15:51:48 -08:00
m32r Merge branch 'for-next' of git://git.infradead.org/users/dhowells/linux-headers 2012-01-14 18:03:30 -08:00
m68k treewide: convert uses of ATTRIB_NORETURN to __noreturn 2012-01-12 20:13:03 -08:00
microblaze Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
mips Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
mn10300 Merge branch 'for-next' of git://git.infradead.org/users/dhowells/linux-headers 2012-01-14 18:03:30 -08:00
openrisc Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2012-01-16 14:34:54 -08:00
parisc parisc, exec: remove redundant set_fs(USER_DS) 2012-01-12 20:13:04 -08:00
powerpc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
score cpu: Register a generic CPU device on architectures that currently do not 2012-01-11 15:50:11 -08:00
sh Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
sparc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
tile Merge branch 'for-next' of git://git.infradead.org/users/dhowells/linux-headers 2012-01-14 18:03:30 -08:00
um Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
unicore32 Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci 2012-01-11 18:50:26 -08:00
x86 Merge branches 'sched-urgent-for-linus', 'perf-urgent-for-linus' and 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-19 14:53:06 -08:00
xtensa audit: inline audit_syscall_entry to reduce burden on archs 2012-01-17 16:16:56 -05:00
.gitignore
Kconfig mm,x86,um: move CMPXCHG_DOUBLE config option 2012-01-12 20:13:03 -08:00