lkml.org 
[lkml]   [2014]   [Apr]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/6] mips: call find_vma with the mmap_sem held
On Sat, Apr 19, 2014 at 07:26:28PM -0700, Davidlohr Bueso wrote:
> Performing vma lookups without taking the mm->mmap_sem is asking
> for trouble. While doing the search, the vma in question can be
> modified or even removed before returning to the caller. Take the
> lock (exclusively) in order to avoid races while iterating through
> the vmacache and/or rbtree.
>
> Updates two functions:
> - process_fpemu_return()
> - cteon_flush_cache_sigtramp()
>
> This patch is completely *untested*.
>
> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: linux-mips@linux-mips.org

Tested-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>


Thanks,

Andreas

> ---
> arch/mips/kernel/traps.c | 2 ++
> arch/mips/mm/c-octeon.c | 2 ++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
> index 074e857..c51bd20 100644
> --- a/arch/mips/kernel/traps.c
> +++ b/arch/mips/kernel/traps.c
> @@ -712,10 +712,12 @@ int process_fpemu_return(int sig, void __user *fault_addr)
> si.si_addr = fault_addr;
> si.si_signo = sig;
> if (sig == SIGSEGV) {
> + down_read(&current->mm->mmap_sem);
> if (find_vma(current->mm, (unsigned long)fault_addr))
> si.si_code = SEGV_ACCERR;
> else
> si.si_code = SEGV_MAPERR;
> + up_read(&current->mm->mmap_sem);
> } else {
> si.si_code = BUS_ADRERR;
> }
> diff --git a/arch/mips/mm/c-octeon.c b/arch/mips/mm/c-octeon.c
> index f41a5c5..05b1d7c 100644
> --- a/arch/mips/mm/c-octeon.c
> +++ b/arch/mips/mm/c-octeon.c
> @@ -137,8 +137,10 @@ static void octeon_flush_cache_sigtramp(unsigned long addr)
> {
> struct vm_area_struct *vma;
>
> + down_read(&current->mm->mmap_sem);
> vma = find_vma(current->mm, addr);
> octeon_flush_icache_all_cores(vma);
> + up_read(&current->mm->mmap_sem);
> }
>
>
> --
> 1.8.1.4
>
>


\
 
 \ /
  Last update: 2014-04-22 18:01    [W:0.144 / U:1.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site