On Thu, Jan 10, 2019 at 8:40 PM Paul Burton [off-list ref] wrote:

On Thu, Jan 10, 2019 at 05:24:31PM +0100, Arnd Bergmann wrote:

quoted

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@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@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?

Up to you: if you want to merge it for 5.0, I'll just drop it from my tree.

If the former then:

  Acked-by: Paul Burton [off-list ref]

Thanks!

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

Do you know of anyone actually still using n32 in production systems
with 4.x kernels? I wonder if it just fell out of popularity as the 64-bit
machines that used it either became large enough to want 64-bit
user space, or got replaced by arm64 or mips32 hardware.

      Arnd
_______________________________________________
Y2038 mailing list
Y2038@lists.linaro.org
https://lists.linaro.org/mailman/listinfo/y2038