linux/arch
Linus Torvalds 9063c61fd5 x86, 64-bit: Clean up user address masking
The discussion about using "access_ok()" in get_user_pages_fast() (see
commit 7f81890687: "x86: don't use
'access_ok()' as a range check in get_user_pages_fast()" for details and
end result), made us notice that x86-64 was really being very sloppy
about virtual address checking.

So be way more careful and straightforward about masking x86-64 virtual
addresses:

 - All the VIRTUAL_MASK* variants now cover half of the address
   space, it's not like we can use the full mask on a signed
   integer, and the larger mask just invites mistakes when
   applying it to either half of the 48-bit address space.

 - /proc/kcore's kc_offset_to_vaddr() becomes a lot more
   obvious when it transforms a file offset into a
   (kernel-half) virtual address.

 - Unify/simplify the 32-bit and 64-bit USER_DS definition to
   be based on TASK_SIZE_MAX.

This cleanup and more careful/obvious user virtual address checking also
uncovered a buglet in the x86-64 implementation of strnlen_user(): it
would do an "access_ok()" check on the whole potential area, even if the
string itself was much shorter, and thus return an error even for valid
strings. Our sloppy checking had hidden this.

So this fixes 'strnlen_user()' to do this properly, the same way we
already handled user strings in 'strncpy_from_user()'.  Namely by just
checking the first byte, and then relying on fault handling for the
rest.  That always works, since we impose a guard page that cannot be
mapped at the end of the user space address space (and even if we
didn't, we'd have the address space hole).

Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-20 15:40:00 -07:00
..
alpha Delete pcibios_select_root 2009-06-17 14:04:42 -07:00
arm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input 2009-06-20 10:17:02 -07:00
avr32 ptrace: remove PT_DTRACE from avr32, mn10300, parisc, s390, sh, xtensa 2009-06-18 13:03:48 -07:00
blackfin Blackfin: convert page/tlb to asm-generic 2009-06-18 21:42:30 -04:00
cris kmap_types: make most arches use generic header file 2009-06-16 19:47:51 -07:00
frv mm: consolidate init_mm definition 2009-06-16 19:47:28 -07:00
h8300 ptrace: remove PT_DTRACE from arch/h8300 2009-06-18 13:03:48 -07:00
ia64 dma-mapping: ia64: add CONFIG_DMA_API_DEBUG support 2009-06-18 13:03:58 -07:00
m32r ptrace: remove PT_DTRACE from arch/m32r 2009-06-18 13:03:49 -07:00
m68k ptrace: remove PT_DTRACE from m68k, m68knommu 2009-06-18 13:03:48 -07:00
m68knommu ptrace: remove PT_DTRACE from m68k, m68knommu 2009-06-18 13:03:48 -07:00
microblaze microblaze: Add missing symbols for CONSTRUCTORS support 2009-06-20 14:36:58 +02:00
mips Delete pcibios_select_root 2009-06-17 14:04:42 -07:00
mn10300 MN10300: Add support for new ELF relocs in kernel modules 2009-06-18 13:10:33 -07:00
parisc ptrace: remove PT_DTRACE from avr32, mn10300, parisc, s390, sh, xtensa 2009-06-18 13:03:48 -07:00
powerpc Merge branch 'perfcounters-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-20 11:29:32 -07:00
s390 Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-06-20 10:56:46 -07:00
sh Merge git://git.kernel.org/pub/scm/linux/kernel/git/lethal/sh-2.6 2009-06-18 14:07:35 -07:00
sparc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next-2.6 2009-06-19 17:42:01 -07:00
um Merge branch 'akpm' 2009-06-16 19:50:13 -07:00
x86 x86, 64-bit: Clean up user address masking 2009-06-20 15:40:00 -07:00
xtensa ptrace: remove PT_DTRACE from avr32, mn10300, parisc, s390, sh, xtensa 2009-06-18 13:03:48 -07:00
.gitignore
Kconfig gcov: add gcov profiling infrastructure 2009-06-18 13:03:57 -07:00