Messages in this thread | | | Date | Sat, 28 Mar 2020 01:26:01 -0700 | From | Christoph Hellwig <> | Subject | Re: [PATCH v2 1/2] nvme: Fix compat NVME_IOCTL_SUBMIT_IO numbering |
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On Sat, Mar 28, 2020 at 01:09:08AM -0400, Nick Bowler wrote: > When __u64 has 64-bit alignment, the nvme_user_io structure has trailing > padding. This causes problems in the compat case with 32-bit userspace > that has less strict alignment because the size of the structure differs. > > Since the NVME_IOCTL_SUBMIT_IO macro encodes the structure size itself, > the result is that this ioctl does not work at all in such a scenario: > > # nvme read /dev/nvme0n1 -z 512 > submit-io: Inappropriate ioctl for device > > But by the same token, this makes it easy to handle both cases and > since the structures differ only in unused trailing padding bytes > we can simply not read those bytes. > > Signed-off-by: Nick Bowler <nbowler@draconx.ca>
I think we already have a similar patch titled "nvme: Add compat_ioctl handler for NVME_IOCTL_SUBMIT_IO" in linux-next, with the difference of actually implementing the .compat_ioctl entry point.
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