Re: [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 > Cc: Ralf Baechle > Cc: linux-m...@linux-mips.org Tested-by: Andreas Herrmann 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(>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(>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(>mm->mmap_sem); > vma = find_vma(current->mm, addr); > octeon_flush_icache_all_cores(vma); > + up_read(>mm->mmap_sem); > } > > > -- > 1.8.1.4 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [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 davidl...@hp.com Cc: Ralf Baechle r...@linux-mips.org Cc: linux-m...@linux-mips.org Tested-by: Andreas Herrmann andreas.herrm...@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 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/