Re: [Qemu-devel] [PATCH] qemu-io-cmds: Assert that global and nofile commands don't use ct->perms

[Max Reitz <mreitz@redhat.com>]

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On 31.03.2017 15:38, Peter Maydell wrote:
> It would be a bug for a command with the CMD_NOFILE_OK or
> CMD_FLAG_GLOBAL flags set to also set the ct->perms field,
> because the former says "OK for a file not to be open"
> but the latter is a check on a file.
> 
> Add an assertion in qemuio_add_command() so we can catch that
> sort of buggy command definition immediately rather than it
> being a bug that only manifests when a particular set of
> command line options is used.
> 
> (Coverity gets confused about this (CID 1371723) and reports
> that we might dereference a NULL blk pointer in this case,
> because it can't tell that that code path never happens with
> the cmdinfo_t that we have. This commit won't help unconfuse
> it, but it does fix the underlying issue.)
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
> We could also try to add some kind of assert in command() to
> persuade coverity that it can't get there with a NULL block
> and ct->perms non-zero, but I think I'd rather just mark the
> issue as a false-positive and move on.

I think having the assertion in qemuio_add_command() is nicer because if
we break it we will definitely notice just by launching qemu-io.

>  qemu-io-cmds.c | 7 +++++++
>  1 file changed, 7 insertions(+)

Thanks, applied to my block branch:

https://github.com/XanClic/qemu/commits/block

Max


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