From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60856 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750721AbcFDSkr (ORCPT ); Sat, 4 Jun 2016 14:40:47 -0400 Subject: Patch "MIPS: Avoid using unwind_stack() with usermode" has been added to the 4.4-stable tree To: james.hogan@imgtec.com, Leonid.Yegoshin@imgtec.com, gregkh@linuxfoundation.org, ralf@linux-mips.org Cc: , From: Date: Sat, 04 Jun 2016 11:40:46 -0700 Message-ID: <1465065646112101@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled MIPS: Avoid using unwind_stack() with usermode to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mips-avoid-using-unwind_stack-with-usermode.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 81a76d7119f63c359750e4adeff922a31ad1135f Mon Sep 17 00:00:00 2001 From: James Hogan Date: Fri, 4 Dec 2015 22:25:02 +0000 Subject: MIPS: Avoid using unwind_stack() with usermode From: James Hogan commit 81a76d7119f63c359750e4adeff922a31ad1135f upstream. When showing backtraces in response to traps, for example crashes and address errors (usually unaligned accesses) when they are set in debugfs to be reported, unwind_stack will be used if the PC was in the kernel text address range. However since EVA it is possible for user and kernel address ranges to overlap, and even without EVA userland can still trigger an address error by jumping to a KSeg0 address. Adjust the check to also ensure that it was running in kernel mode. I don't believe any harm can come of this problem, since unwind_stack() is sufficiently defensive, however it is only meant for unwinding kernel code, so to be correct it should use the raw backtracing instead. Signed-off-by: James Hogan Reviewed-by: Leonid Yegoshin Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11701/ Signed-off-by: Ralf Baechle (cherry picked from commit d2941a975ac745c607dfb590e92bb30bc352dad9) Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/traps.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -144,7 +144,7 @@ static void show_backtrace(struct task_s if (!task) task = current; - if (raw_show_trace || !__kernel_text_address(pc)) { + if (raw_show_trace || user_mode(regs) || !__kernel_text_address(pc)) { show_raw_backtrace(sp); return; } Patches currently in stable-queue which might be from james.hogan@imgtec.com are queue-4.4/mips64-r6-r2-emulation-bugfix.patch queue-4.4/mips-fix-uapi-include-in-exported-asm-siginfo.h.patch queue-4.4/mips-disable-preemption-during-prctl-pr_set_fp_mode.patch queue-4.4/mips-fix-sigreturn-via-vdso-on-micromips-kernel.patch queue-4.4/mips-fix-siginfo.h-to-use-strict-posix-types.patch queue-4.4/mips-don-t-unwind-to-user-mode-with-eva.patch queue-4.4/mips-vdso-build-with-fno-strict-aliasing.patch queue-4.4/mips-fix-watchpoint-restoration.patch queue-4.4/mips-build-micromips-vdso-for-micromips-kernels.patch queue-4.4/mips-math-emu-fix-jalr-emulation-when-rd-0.patch queue-4.4/mips-fix-msa-ld_-st_-asm-macros-to-use-ptr_addu.patch queue-4.4/mips-avoid-using-unwind_stack-with-usermode.patch queue-4.4/mips-prevent-restoration-of-msa-context-in-non-msa-kernels.patch queue-4.4/mips-use-copy_s.fmt-rather-than-copy_u.fmt.patch