c95b708d5f
On a 32-bit kernel, the upper bits of userspace addresses passed via various ioctls are silently ignored by the nvme driver. However on a 64-bit kernel running a compat task, these upper bits are not ignored and are in fact required to be zero for the ioctls to work. Unfortunately, this difference matters. 32-bit smartctl submits the NVME_IOCTL_ADMIN_CMD ioctl with garbage in these upper bits because it seems the pointer value it puts into the nvme_passthru_cmd structure is sign extended. This works fine on 32-bit kernels but fails on a 64-bit one because (at least on my setup) the addresses smartctl uses are consistently above 2G. For example: # smartctl -x /dev/nvme0n1 smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.5.11] (local build) Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org Read NVMe Identify Controller failed: NVME_IOCTL_ADMIN_CMD: Bad address Since changing 32-bit kernels to actually check all of the submitted address bits now would break existing userspace, this patch fixes the compat problem by explicitly zeroing the upper bits in the compat case. This enables 32-bit smartctl to work on a 64-bit kernel. Signed-off-by: Nick Bowler <nbowler@draconx.ca> Signed-off-by: Christoph Hellwig <hch@lst.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.