From f7a89f1b8eb598ac5da61c9795b3d847baa73d12 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Sat, 19 Apr 2014 19:26:28 -0700 Subject: [PATCH] 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 Tested-by: Andreas Herrmann 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 --- 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 8119ac2fdfc9..d57fc10df773 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(¤t->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(¤t->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 f41a5c5b0865..05b1d7cf9514 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(¤t->mm->mmap_sem); vma = find_vma(current->mm, addr); octeon_flush_icache_all_cores(vma); + up_read(¤t->mm->mmap_sem); }