Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1731103

[PATCH 4.4 30/31] ARM: 8692/1: mm: abort uaccess retries upon fatal signal

Show all headers | View raw

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Rutland <mark.rutland@arm.com>

commit 746a272e44141af24a02f6c9b0f65f4c4598ed42 upstream.

When there's a fatal signal pending, arm's do_page_fault()
implementation returns 0. The intent is that we'll return to the
faulting userspace instruction, delivering the signal on the way.

However, if we take a fatal signal during fixing up a uaccess, this
results in a return to the faulting kernel instruction, which will be
instantly retried, resulting in the same fault being taken forever. As
the task never reaches userspace, the signal is not delivered, and the
task is left unkillable. While the task is stuck in this state, it can
inhibit the forward progress of the system.

To avoid this, we must ensure that when a fatal signal is pending, we
apply any necessary fixup for a faulting kernel instruction. Thus we
will return to an error path, and it is up to that code to make forward
progress towards delivering the fatal signal.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/mm/fault.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -314,8 +314,11 @@ retry:
 	 * signal first. We do not need to release the mmap_sem because
 	 * it would already be released in __lock_page_or_retry in
 	 * mm/filemap.c. */
-	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
+		if (!user_mode(regs))
+			goto no_context;
 		return 0;
+	}
 
 	/*
 	 * Major/minor page fault accounting is only done on the

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 4.4 00/31] 4.4.88-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:00 +0200
  [PATCH 4.4 01/31] usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:00 +0200
  [PATCH 4.4 26/31] btrfs: resume qgroup rescan on rw remount Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 15/31] mwifiex: correct channel stat buffer overflows Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 28/31] ALSA: msnd: Optimize / harden DSP and MIDI loops Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 05/31] USB: core: Avoid race of async_completed() w/ usbdev_release() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 12/31] rtlwifi: rtl_pci_probe: Fix fail path of _rtl_pci_find_adapter Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 04/31] usb:xhci:Fix regression when ATI chipsets detected Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 09/31] intel_th: pci: Add Cannon Lake PCH-LP support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 06/31] staging/rts5208: fix incorrect shift to extract upper nybble Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 13/31] Bluetooth: Add support of 13d3:3494 RTL8723BE device Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 21/31] drm: adv7511: really enable interrupts for EDID detection Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 22/31] drm/bridge: adv7511: Fix mutex deadlock when interrupts are disabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 11/31] Input: trackpoint - assume 3 buttons when buttons detection fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 07/31] driver core: bus: Fix a potential double free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 16/31] drm/nouveau/pci/msi: disable MSI on big-endian platforms by default Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 30/31] ARM: 8692/1: mm: abort uaccess retries upon fatal signal Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 18/31] cs5536: add support for IDE controller variant Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 03/31] usb: Add device quirk for Logitech HD Pro Webcam C920-C Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  [PATCH 4.4 23/31] drm/bridge: adv7511: Use work_struct to defer hotplug handing to out of irq context Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-12 19:20 +0200
  Re: [PATCH 4.4 00/31] 4.4.88-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-13 02:20 +0200
  Re: [PATCH 4.4 00/31] 4.4.88-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-13 03:10 +0200
    Re: [PATCH 4.4 00/31] 4.4.88-stable review Kevin Hilman <khilman@baylibre.com> - 2017-09-14 00:00 +0200
      Re: [PATCH 4.4 00/31] 4.4.88-stable review Stephen Boyd <sboyd@codeaurora.org> - 2017-09-19 08:00 +0200
        Re: [PATCH 4.4 00/31] 4.4.88-stable review Mark Brown <broonie@kernel.org> - 2017-09-19 13:20 +0200
  Re: [PATCH 4.4 00/31] 4.4.88-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-13 16:40 +0200

csiph-web