From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Slaby Date: Sun, 17 Oct 2010 17:46:15 +0000 Subject: Re: [PATCH 6/8] char: synclink: fix information leak to userland Message-Id: <4CBB3667.2010804@suse.cz> List-Id: References: <1287326493-8134-1-git-send-email-segooon@gmail.com> <4CBB177C.9050007@suse.cz> <20101017153839.GA11029@albatros> In-Reply-To: <20101017153839.GA11029@albatros> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vasiliy Kulikov Cc: kernel-janitors@vger.kernel.org, Greg Kroah-Hartman , Alan Cox , Arnd Bergmann , linux-kernel@vger.kernel.org On 10/17/2010 05:38 PM, Vasiliy Kulikov wrote: > On Sun, Oct 17, 2010 at 17:34 +0200, Jiri Slaby wrote: >> On 10/17/2010 04:41 PM, Vasiliy Kulikov wrote: >>> Structure new_line is copied to userland with some padding fields unitialized. >>> It leads to leaking of stack memory. >> >> I think your tool has a bug. I must admit I fail to see the padding >> which would cause leaks. Could you elaborate? > > I didn't use any tool except "grep copy_to_user" :) > > typedef struct { > unsigned int clock_rate; /* bits per second */ > unsigned int clock_type; /* internal, external, TX-internal etc. */ > unsigned short loopback; > } sync_serial_settings; /* V.35, V.24, X.21 */ > > On x86_64 sizeof(sync_serial_settings) = 4 + 4 + 2 + 2 = 12. > The last 2 is padding. Ah, good to know that even end of structures is padded. thanks for clarification, -- js suse labs