linux-kernel - Re: [PATCH v3 2/3] x86/signal: Rewire the restart

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Date:	Tue, 21 Jun 2016 13:39:56 +0100
From:	Pedro Alves <palves@...hat.com>
To:	Andy Lutomirski <luto@...nel.org>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc:	Borislav Petkov <bp@...en8.de>, Oleg Nesterov <oleg@...hat.com>,
	Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v3 2/3] x86/signal: Rewire the restart_block() syscall to
 have a constant nr

Hi Andy,

On 06/21/2016 12:39 AM, Andy Lutomirski wrote:
> Suppose a 64-bit task A traces a 32-bit task B.

I gave your x86/ptrace branch a try:

 https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/log/?h=x86/ptrace

(this looks to be the same patch set.)

Unfortunately, with gdb git master, I still get the
64-bit ptracer x 32-bit ptracee problem:

 (gdb) r
 Starting program: interrupt.32 
 talk to me baby
 ^C

 Program received signal SIGINT, Interrupt.
 0xf7fd9d09 in __kernel_vsyscall ()
 (gdb) p func1 ()
 $1 = 4
 (gdb) c
 Continuing.
 Unknown error 512
 [Inferior 1 (process 2198) exited with code 01]
 (gdb) q

Is this expected?

This is the same testcase as before:

 https://sourceware.org/ml/gdb/2014-05/msg00004.html

Thanks,
Pedro Alves