From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.deacon@arm.com (Will Deacon)
Date: Fri, 25 Jul 2014 12:03:42 +0100
Subject: [PATCH v5 1/3] arm64: ptrace: reload a syscall number after
 ptrace operations
In-Reply-To: <53D23341.4040403@linaro.org>
References: <1406020499-5537-1-git-send-email-takahiro.akashi@linaro.org>
 <1406020499-5537-2-git-send-email-takahiro.akashi@linaro.org>
 <53D08358.4020902@amacapital.net> <53D0A037.2060308@linaro.org>
 <CALCETrU9_sdODRz-xZ4bouq+anHhmfx2tkr7hg00RVf_bBBJwg@mail.gmail.com>
 <53D23341.4040403@linaro.org>
Message-ID: <20140725110342.GD5269@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Fri, Jul 25, 2014 at 11:36:49AM +0100, AKASHI Takahiro wrote:
> On 07/25/2014 12:01 AM, Andy Lutomirski wrote:
> >>> If so, then you risk (at least) introducing
> >>>
> >>> a nice user-triggerable OOPS if audit is enabled.
> >>
> >>
> >> Can you please elaborate this?
> >> Since I didn't find any definition of audit's behavior when syscall is
> >> rewritten to -1, I thought it is reasonable to skip "exit tracing" of
> >> "skipped" syscall.
> >> (otherwise, "fake" seems to be more appropriate :)
> >
> > The audit entry hook will oops if you call it twice in a row without
> > calling the exit hook in between.
> 
> Thank you, I could reproduce this problem which hits BUG(in_syscall) in
> audit_syscall_entry(). Really bad, and I fixed it in my next version and
> now a "skipped" system call is also traced by audit.

Can you reproduce this on arch/arm/ too? If so, we should also fix the code
there.

Will