[PATCH 11/15] mips: fix n32 compat_ipc_parse_version

[Paul Burton]

Hi Arnd,

On Thu, Jan 10, 2019 at 05:24:31PM +0100, Arnd Bergmann wrote:
> While reading through the sysvipc implementation, I noticed that the n32
> semctl/shmctl/msgctl system calls behave differently based on whether
> o32 support is enabled or not: Without o32, the IPC_64 flag passed by
> user space is rejected but calls without that flag get IPC_64 behavior.
> 
> As far as I can tell, this was inadvertently changed by a cleanup patch
> but never noticed by anyone, possibly nobody has tried using sysvipc
> on n32 after linux-3.19.
> 
> Change it back to the old behavior now.
> 
> Fixes: 78aaf956ba3a ("MIPS: Compat: Fix build error if CONFIG_MIPS32_COMPAT but no compat ABI.")
> Cc: stable at vger.kernel.org
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> ---
> As stated above, this was only found by inspection, the patch is not
> tested. Please review accordingly.

Nice catch! Would you prefer to merge this yourself, or that I take it
through the mips tree?

If the former then:

  Acked-by: Paul Burton <paul.burton at mips.com>

I suspect kernels configured with n32 support but no o32 support are
probably not very common - for internal testing we currently always
enable both.

Thanks,
    Paul

> ---
>  arch/mips/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 787290781b8c..0d14f51d0002 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -3155,6 +3155,7 @@ config MIPS32_O32
>  config MIPS32_N32
>  	bool "Kernel support for n32 binaries"
>  	depends on 64BIT
> +	select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
>  	select COMPAT
>  	select MIPS32_COMPAT
>  	select SYSVIPC_COMPAT if SYSVIPC
> -- 
> 2.20.0
>