From: Andrew Morton <akpm@linux-foundation.org>
To: Maxim Zhukov <crazycdeveloper@gmail.com>
Cc: chi.minghao@zte.com.cn, varad.gautam@suse.com, arnd@arndb.de,
shakeelb@google.com, vasily.averin@linux.dev,
manfred@colorfullife.com, dbueso@suse.de,
linux-kernel@vger.kernel.org,
Maxim Zhukov <mussitantesmortem@gmail.com>
Subject: Re: [RFC PATCH 1/1] ipc, sem: fix backward compatibility with x86-32 kernels
Date: Mon, 16 May 2022 14:06:20 -0700 [thread overview]
Message-ID: <20220516140620.85f84d560c85d01d48dae917@linux-foundation.org> (raw)
In-Reply-To: <20220515200103.1408370-2-mussitantesmortem@gmail.com>
On Sun, 15 May 2022 23:01:03 +0300 Maxim Zhukov <crazycdeveloper@gmail.com> wrote:
> Since with commit 275f22148e87 ("ipc: rename old-style shmctl/semctl/msgctl syscalls")
> we have changed behavior:
>
> ksys_semctl lost parse ipc version (ipc_parse_version), because the
> new syscall works with IPC_64 only, but the parse function has some
> side effect - it removes IPC_64 bit from `cmd`.
>
> Some libc forced sends IPC_64 bit in semctl syscall[1][2][3], this leads to
> a bug - X86-32 kernel does not have compat headers and does not
> correctly parse received command (cmd) from semctl syscall: cmd have actual
> command and IPC_64 bit, thus throw EINVAL error in ksys_semctl
>
> This commit forcibly removes IPC_64 bit from the cmd for restore
> backward compatibility.
>
> [1]: https://elixir.bootlin.com/uclibc-ng/v1.0.40/source/libc/misc/sysvipc/sem.c#L58
> [2]: https://elixir.bootlin.com/musl/v1.2.3/source/src/ipc/semctl.c#L48 -> https://elixir.bootlin.com/musl/v1.2.3/source/src/ipc/ipc.h#L22
> [3]: https://elixir.bootlin.com/glibc/glibc-2.35/source/sysdeps/unix/sysv/linux/semctl.c#L124
>
Thanks.
275f22148e87 was three years ago. Can you suggest why it took so long
for this to be discovered?
next prev parent reply other threads:[~2022-05-16 21:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-15 20:01 [RFC PATCH 0/1] Fix handling semctl on x86-32 kernels Maxim Zhukov
2022-05-15 20:01 ` [RFC PATCH 1/1] ipc, sem: fix backward compatibility with " Maxim Zhukov
2022-05-16 21:06 ` Andrew Morton [this message]
2022-05-16 22:07 ` Arnd Bergmann
2022-05-16 22:00 ` Arnd Bergmann
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