compat: Make compat_alloc_user_space() incorporate the access_ok()
authorH. Peter Anvin <hpa@linux.intel.com>
Tue, 7 Sep 2010 23:16:18 +0000 (16:16 -0700)
committerH. Peter Anvin <hpa@linux.intel.com>
Tue, 14 Sep 2010 23:08:45 +0000 (16:08 -0700)
commitc41d68a513c71e35a14f66d71782d27a79a81ea6
tree2729377678b4f0fa516404eec6c3a87a4fd7c823
parentbfa88ea7ee9e6b4fd673e45a8cc0a8e0b7ef4761
compat: Make compat_alloc_user_space() incorporate the access_ok()

compat_alloc_user_space() expects the caller to independently call
access_ok() to verify the returned area.  A missing call could
introduce problems on some architectures.

This patch incorporates the access_ok() check into
compat_alloc_user_space() and also adds a sanity check on the length.
The existing compat_alloc_user_space() implementations are renamed
arch_compat_alloc_user_space() and are used as part of the
implementation of the new global function.

This patch assumes NULL will cause __get_user()/__put_user() to either
fail or access userspace on all architectures.  This should be
followed by checking the return value of compat_access_user_space()
for NULL in the callers, at which time the access_ok() in the callers
can also be removed.

Reported-by: Ben Hawkes <hawkes@sota.gen.nz>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: James Bottomley <jejb@parisc-linux.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: <stable@kernel.org>
arch/ia64/include/asm/compat.h
arch/mips/include/asm/compat.h
arch/parisc/include/asm/compat.h
arch/powerpc/include/asm/compat.h
arch/s390/include/asm/compat.h
arch/sparc/include/asm/compat.h
arch/tile/include/asm/compat.h
arch/x86/include/asm/compat.h
include/linux/compat.h
kernel/compat.c