From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasiliy Kulikov Date: Sun, 17 Oct 2010 17:50:06 +0000 Subject: Re: [PATCH 6/8] char: synclink: fix information leak to userland Message-Id: <20101017175006.GA14278@albatros> List-Id: References: <1287326493-8134-1-git-send-email-segooon@gmail.com> <4CBB177C.9050007@suse.cz> <20101017153839.GA11029@albatros> <20101017173609.GS6614@bicker> In-Reply-To: <20101017173609.GS6614@bicker> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Dan Carpenter , Jiri Slaby , kernel-janitors@vger.kernel.org, Greg Kroah-Hartman , Alan Cox , Arnd Bergmann , linux-kernel@vger.kernel.org On Sun, Oct 17, 2010 at 19:36 +0200, Dan Carpenter wrote: > On Sun, Oct 17, 2010 at 07:38:39PM +0400, 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" :) > > > > It seems like you should be able to use pahole to make a list of > structs with padding and then a checker script to find places where > information is leaked. Not all of these patches fix only padding zeroing, some of them fix uninitialized fields. One struct has partly initialized array. > Also someone complained to me about when I added a memset() in a fast > path. All these cases are ioctl() handlers or similar. I don't think ioctl() should be so fast to become significantly slower with single memset(). > The thought was that it might be faster to just initialize it > instead like: > > struct foo bar = {}; > > In my case just using the initializer made the code cleaner so I did it, > but neither of us actually benchmarked it. > > regards, > dan carpenter > -- > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Thanks, -- Vasiliy