Messages in this thread | | | Date | Tue, 8 Dec 2009 22:26:12 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH] futex: Take mmap_sem for get_user_pages in fault_in_user_writeable |
| |
On Tue, Dec 08, 2009 at 01:19:42PM +0100, Andi Kleen wrote: > futex: Take mmap_sem for get_user_pages in fault_in_user_writeable > > gup() requires mmap_sem, so take it before running it. The > recent fault_in_user_writeable() didn't do that. > > I didn't find a good futex test case, so untested. > > Likely a stable candidate. > > Cc: npiggin@suse.de > Cc: tglx@linutronix.de > Cc: dvhltc@us.ibm.com > Signed-off-by: Andi Kleen <ak@linux.intel.com>
I agree it should go to .stable.
Acked-by: Nick Piggin <npiggin@suse.de>
> --- > kernel/futex.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > Index: linux-2.6.32-ak/kernel/futex.c > =================================================================== > --- linux-2.6.32-ak.orig/kernel/futex.c > +++ linux-2.6.32-ak/kernel/futex.c > @@ -304,8 +304,13 @@ void put_futex_key(int fshared, union fu > */ > static int fault_in_user_writeable(u32 __user *uaddr) > { > - int ret = get_user_pages(current, current->mm, (unsigned long)uaddr, > + int ret; > + struct mm_struct *mm = current->mm; > + > + down_read(&mm->mmap_sem); > + ret = get_user_pages(current, mm, (unsigned long)uaddr, > 1, 1, 0, NULL, NULL); > + up_read(&mm->mmap_sem); > return ret < 0 ? ret : 0; > } >
| |