From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>, x86@kernel.org
Cc: LKML <linux-kernel@vger.kernel.org>,
Andy Lutomirski <luto@kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 2/3] x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls
Date: Mon, 01 Mar 2021 16:36:40 +0100 [thread overview]
Message-ID: <87h7luubqv.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <04713c6be5ab45357e3406c42d382536f52a64c6.1614104065.git.luto@kernel.org>
On Tue, Feb 23 2021 at 10:15, Andy Lutomirski wrote:
> On a 32-bit fast syscall that fails to read its arguments from user
> memory, the kernel currently does syscall exit work but not
> syscall entry work. This confuses audit and ptrace. For example:
>
> $ ./tools/testing/selftests/x86/syscall_arg_fault_32
> ...
> strace: pid 264258: entering, ptrace_syscall_info.op == 2
> ...
>
> This is a minimal fix intended for ease of backporting. A more
> complete cleanup is coming.
>
> Cc: stable@vger.kernel.org
> Fixes: 0b085e68f407 ("x86/entry: Consolidate 32/64 bit syscall entry")
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> arch/x86/entry/common.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
> index 0904f5676e4d..cf4dcf346ca8 100644
> --- a/arch/x86/entry/common.c
> +++ b/arch/x86/entry/common.c
> @@ -128,7 +128,8 @@ static noinstr bool __do_fast_syscall_32(struct pt_regs *regs)
> regs->ax = -EFAULT;
>
> instrumentation_end();
> - syscall_exit_to_user_mode(regs);
> + local_irq_disable();
> + exit_to_user_mode();
That's still the same as the previous version. The right function (while
the name is misleading) to invoke here is irqentry_exit_to_user_mode()
because that invokes exit_to_user_mode_prepare() before
exit_to_user_mode(). We can rename that function afterwards.
Thanks,
tglx
next prev parent reply other threads:[~2021-03-01 15:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 18:15 [PATCH v2 0/3] x86/entry: A compat syscall bugfix and some test stuff Andy Lutomirski
2021-02-23 18:15 ` [PATCH v2 1/3] entry: Check that syscall entries and syscall exits match Andy Lutomirski
2021-02-23 18:15 ` [PATCH v2 2/3] x86/entry: Fix entry/exit mismatch on failed fast 32-bit syscalls Andy Lutomirski
2021-03-01 15:36 ` Thomas Gleixner [this message]
2021-02-23 18:15 ` [PATCH v2 3/3] selftests/x86: Add a missing .note.GNU-stack section to thunks_32.S Andy Lutomirski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87h7luubqv.fsf@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=stable@vger.kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).