From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To: Rich Felker <dalias@libc.org>, linux-sh@vger.kernel.org
Cc: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>,
linux-kernel@vger.kernel.org,
Yoshinori Sato <ysato@users.sourceforge.jp>
Subject: Re: [PATCH] sh: fix syscall tracing
Date: Thu, 03 Sep 2020 08:13:43 +0000 [thread overview]
Message-ID: <65bf8a3b-8213-0a67-1156-043bca545ada@physik.fu-berlin.de> (raw)
In-Reply-To: <20200903054803.GX3265@brightrain.aerifal.cx>
Hi Rich!
On 9/3/20 7:48 AM, Rich Felker wrote:
> Addition of SECCOMP_FILTER exposed a longstanding bug in
> do_syscall_trace_enter, whereby r0 (the 5th argument register) was
> mistakenly used where r3 (syscall_nr) was intended. By overwriting r0
> rather than r3 with -1 when attempting to block a syscall, the
> existing code would instead have caused the syscall to execute with an
> argument clobbered.
>
> Commit 0bb605c2c7f2b4b3 then introduced skipping of the syscall when
> do_syscall_trace_enter returns -1, so that the return value set by
> seccomp filters would not be clobbered by -ENOSYS. This eliminated the
> clobbering of the 5th argument register, but instead caused syscalls
> made with a 5th argument of -1 to be misinterpreted as a request by
> do_syscall_trace_enter to suppress the syscall.
>
> Fixes: 0bb605c2c7f2b4b3 ("sh: Add SECCOMP_FILTER")
> Fixes: ab99c733ae73cce3 ("sh: Make syscall tracer use tracehook notifiers, add TIF_NOTIFY_RESUME.")
> Signed-off-by: Rich Felker <dalias@libc.org>
I'm testing this patch now with a rebased kernel and a rebased libseccomp with my
patch for SuperH support on top.
I'll report back later.
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer - glaubitz@debian.org
`. `' Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
next prev parent reply other threads:[~2020-09-03 8:13 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-03 5:48 [PATCH] sh: fix syscall tracing Rich Felker
2020-09-03 8:13 ` John Paul Adrian Glaubitz [this message]
2020-09-03 10:14 ` John Paul Adrian Glaubitz
2020-09-03 16:16 ` Rich Felker
2020-09-07 9:52 ` John Paul Adrian Glaubitz
2020-09-07 17:44 ` Rich Felker
2020-09-10 9:55 ` John Paul Adrian Glaubitz
2020-09-10 10:54 ` Rob Landley
2020-09-10 13:37 ` Rich Felker
2020-09-15 10:35 ` John Paul Adrian Glaubitz
2020-09-16 0:28 ` Rich Felker
2020-09-18 19:29 ` Rich Felker
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