Commit f7a89f1b authored Apr 19, 2014 by Davidlohr Bueso Committed by Ralf Baechle Jun 03, 2014

MIPS: Call find_vma with the mmap_sem held



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()

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Tested-by: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: akpm@linux-foundation.org
Cc: zeus@gnu.org
Cc: aswin@hp.com
Cc: davidlohr@hp.com
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Patchwork: http://patchwork.linux-mips.org/patch/6811/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

parent 25198235

arch/mips/kernel/traps.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

arch/mips/mm/c-octeon.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}