From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call
Date: Tue, 2 Sep 2014 10:31:22 +0100 [thread overview]
Message-ID: <20140902093121.GL30401@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20140902091622.GK30401@n2100.arm.linux.org.uk>
On Tue, Sep 02, 2014 at 10:16:22AM +0100, Russell King - ARM Linux wrote:
> On Tue, Sep 02, 2014 at 05:47:29PM +0900, AKASHI Takahiro wrote:
> > On 09/01/2014 08:47 PM, Russell King - ARM Linux wrote:
> >> On Wed, Aug 27, 2014 at 02:55:46PM +0900, AKASHI Takahiro wrote:
> >>> 1)
> >>> setting x0 to -ENOSYS is necessary because, otherwise, user-issued syscall(-1) will
> >>> return a bogus value when audit tracing is on.
> >>>
> >>> Please note that, on arm,
> >>> not traced traced
> >>> ------ ------
> >>> syscall(-1) aborted OOPs(BUG_ON)
> >>> syscall(-3000) aborted aborted
> >>> syscall(1000) ENOSYS ENOSYS
> >>
> >> Two points here:
> >>
> >> 1. You've found a case which causes a BUG_ON(). Where is the bug report
> >> for this, so the problem can be investigated and resolved?
> >
> > I think that I mentioned it could also happen on arm somewhere in a talk
> > with Will, but don't remember exactly when.
>
> Sorry, not good enough. Please report this bug so it can be investigated
> and fixed.
I'm going to go further than this, and tell you that you have been
downright irresponsible here, and I'm disgusted by your behaviour over
this.
You have revealed a potential security problem publically, effectively
giving details about how to cause it, but without having first reported
it to people who can fix it, nor providing a fix for it.
Why is it a security problem? Although it can't be used to gain
information, it can be used potentially to deny service. Any user can
trace a task which they own, and then set the task's syscall to -1,
which according to you results in a kernel oops.
If the kernel oops happens while holding any locks, that part of the
system becomes non-functional and can result in all userland stopping
dead.
--
FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up
according to speedtest.net.
next prev parent reply other threads:[~2014-09-02 9:31 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-21 8:56 [PATCH v6 0/6] arm64: add seccomp support AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 1/6] arm64: ptrace: add PTRACE_SET_SYSCALL AKASHI Takahiro
2014-08-21 16:47 ` Kees Cook
2014-08-22 0:19 ` AKASHI Takahiro
2014-08-26 17:46 ` Will Deacon
2014-08-27 5:32 ` AKASHI Takahiro
2014-09-03 18:34 ` Kees Cook
2014-08-21 8:56 ` [PATCH v6 2/6] arm64: ptrace: allow tracer to skip a system call AKASHI Takahiro
2014-08-21 17:08 ` Kees Cook
2014-08-22 0:35 ` AKASHI Takahiro
2014-08-26 17:51 ` Will Deacon
2014-08-27 5:55 ` AKASHI Takahiro
2014-09-01 11:37 ` Will Deacon
2014-09-02 7:58 ` AKASHI Takahiro
2014-09-01 11:47 ` Russell King - ARM Linux
2014-09-02 8:47 ` AKASHI Takahiro
2014-09-02 9:16 ` Russell King - ARM Linux
2014-09-02 9:31 ` Russell King - ARM Linux [this message]
2014-09-05 10:08 ` AKASHI Takahiro
2014-10-01 11:08 ` AKASHI Takahiro
2014-10-03 15:23 ` Will Deacon
2014-10-06 8:04 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 3/6] asm-generic: add generic seccomp.h for secure computing mode 1 AKASHI Takahiro
2014-08-21 17:51 ` Kees Cook
2014-08-22 0:38 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 4/6] arm64: add seccomp syscall for compat task AKASHI Takahiro
2014-08-21 17:52 ` Kees Cook
2014-08-22 0:39 ` AKASHI Takahiro
2014-08-26 17:53 ` Will Deacon
2014-08-27 5:57 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 5/6] arm64: add SIGSYS siginfo " AKASHI Takahiro
2014-08-21 17:54 ` Kees Cook
2014-08-22 0:44 ` AKASHI Takahiro
2014-08-26 17:55 ` Will Deacon
2014-08-27 5:58 ` AKASHI Takahiro
2014-08-21 8:56 ` [PATCH v6 6/6] arm64: add seccomp support AKASHI Takahiro
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