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[PATCH 4.13 44/47] scsi: sg: recheck MMAP_IO request length with lock held

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.13 44/47] scsi: sg: recheck MMAP_IO request length with lock held
Date 2017-09-08 15:50 +0200
Message-ID <unrPs-7GO-23@gated-at.bofh.it> (permalink)
References <unrw5-7zK-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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

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

From: Todd Poynor <toddpoynor@google.com>

commit 8d26f491116feaa0b16de370b6a7ba40a40fa0b4 upstream.

Commit 1bc0eb044615 ("scsi: sg: protect accesses to 'reserved' page
array") adds needed concurrency protection for the "reserve" buffer.
Some checks that are initially made outside the lock are replicated once
the lock is taken to ensure the checks and resulting decisions are made
using consistent state.

The check that a request with flag SG_FLAG_MMAP_IO set fits in the
reserve buffer also needs to be performed again under the lock to ensure
the reserve buffer length compared against matches the value in effect
when the request is linked to the reserve buffer.  An -ENOMEM should be
returned in this case, instead of switching over to an indirect buffer
as for non-MMAP_IO requests.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/scsi/sg.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1741,9 +1741,12 @@ sg_start_req(Sg_request *srp, unsigned c
 		    !sfp->res_in_use) {
 			sfp->res_in_use = 1;
 			sg_link_reserve(sfp, srp, dxfer_len);
-		} else if ((hp->flags & SG_FLAG_MMAP_IO) && sfp->res_in_use) {
+		} else if (hp->flags & SG_FLAG_MMAP_IO) {
+			res = -EBUSY; /* sfp->res_in_use == 1 */
+			if (dxfer_len > rsv_schp->bufflen)
+				res = -ENOMEM;
 			mutex_unlock(&sfp->f_mutex);
-			return -EBUSY;
+			return res;
 		} else {
 			res = sg_build_indirect(req_schp, sfp, dxfer_len);
 			if (res) {

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[PATCH 4.13 00/47] 4.13.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 14/47] iio: adc: ti-ads1015: enable conversion when CONFIG_PM is not set Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 10/47] staging: ccree: save ciphertext for CTS IV Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 24/47] fpga: altera-hps2fpga: fix multiple init of l3_remap_lock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 12/47] iio: adc: ti-ads1015: fix incorrect data rate setting update Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 42/47] cs5536: add support for IDE controller variant Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 16/47] iio: adc: ti-ads1015: dont return invalid value from buffer setup callbacks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 33/47] iwlwifi: pci: add new PCI ID for 7265D Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 36/47] MCB: add support for SC31 to mcb-lpc Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 41/47] ahci: dont use MSI for devices with the silly Intel NVMe remapping scheme Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 09/47] staging/rts5208: fix incorrect shift to extract upper nybble Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 35/47] mwifiex: correct channel stat buffer overflows Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 39/47] drm/nouveau: Fix error handling in nv50_disp_atomic_commit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 01/47] usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 40/47] workqueue: Fix flag collision Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 19/47] HID: wacom: Do not completely map WACOM_HID_WD_TOUCHRINGSTATUS usage Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 18/47] driver core: bus: Fix a potential double free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:30 +0200
  [PATCH 4.13 37/47] s390/mm: avoid empty zero pages for KVM guests to avoid postcopy hangs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 23/47] thunderbolt: Fix reset response_type Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 25/47] intel_th: pci: Add Cannon Lake PCH-H support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 44/47] scsi: sg: recheck MMAP_IO request length with lock held Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 46/47] rtlwifi: Fix memory leak when firmware request fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 31/47] rtlwifi: rtl_pci_probe: Fix fail path of _rtl_pci_find_adapter Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 28/47] drm/vgem: Pin our pages for dmabuf exports Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 38/47] drm/nouveau/pci/msi: disable MSI on big-endian platforms by default Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 26/47] intel_th: pci: Add Cannon Lake PCH-LP support Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 27/47] ath10k: fix memory leak in rx ring buffer allocation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 47/47] rtlwifi: Fix fallback firmware loading Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 43/47] scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 45/47] of/device: Prevent buffer overflow in of_device_modalias() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 32/47] Bluetooth: Add support of 13d3:3494 RTL8723BE device Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 15:50 +0200
  [PATCH 4.13 20/47] binder: free memory on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 15/47] iio: adc: ti-ads1015: avoid getting stale result after runtime resume Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 03/47] usb: Add device quirk for Logitech HD Pro Webcam C920-C Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 13/47] iio: adc: ti-ads1015: fix scale information for ADS1115 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 08/47] USB: core: Avoid race of async_completed() w/ usbdev_release() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 04/47] usb:xhci:Fix regression when ATI chipsets detected Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 05/47] USB: musb: fix external abort on suspend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 07/47] ANDROID: binder: add hwbinder,vndbinder to BINDER_DEVICES. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 17/47] iio: adc: ti-ads1015: add adequate wait time to get correct conversion Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 06/47] ANDROID: binder: add padding to binder_fd_array_object. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  [PATCH 4.13 02/47] USB: serial: option: add support for D-Link DWM-157 C1 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-08 16:00 +0200
  Re: [PATCH 4.13 00/47] 4.13.1-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-08 19:00 +0200
    Re: [PATCH 4.13 00/47] 4.13.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-09 07:50 +0200
  Re: [PATCH 4.13 00/47] 4.13.1-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-09 15:50 +0200
    Re: [PATCH 4.13 00/47] 4.13.1-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-09 16:20 +0200

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