Date: Sat, 30 Jan 2016 14:09:35 -0700 From: Ian Lepore <ian@freebsd.org> To: mokhi <mokhi64@gmail.com>, freebsd-current@freebsd.org Subject: Re: thread-unsafety problems as spl*() ones are NOP Message-ID: <1454188175.32550.3.camel@freebsd.org> In-Reply-To: <CAByVWPWQJ1wP95S59SiWWBa0k9j2%2Bu1az-D04_V1voo99CxqCw@mail.gmail.com> References: <CAByVWPWuqdtZ-5p2%2BvGf4v%2BPjjCBkiTQSsZQ06vk-f=bx_TQrQ@mail.gmail.com> <CAByVWPWQJ1wP95S59SiWWBa0k9j2%2Bu1az-D04_V1voo99CxqCw@mail.gmail.com>
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On Sat, 2016-01-30 at 18:56 +0330, mokhi wrote: > Hi. > in kbd.c there are many places spltty()/splx() used assuming it > locks/unlocks. > though there is bug filed for this, and ive asked in #bsddev, Ive > preferred to ask and ensure it from here again. > As these functions are obsoleted now, this assumption is incorrect > and > some places we have thread-unsafely which leads to security problems > (and/or for example double-free, etc) > > can i use mutex/spin/lock/unlock under where assumed a lock/unlock by > using spltty()/splx() to patch it? > > Thanks, Mokhi. If you start working on locking in keyboard drivers you might discover there are dragons there. For example... https://lists.freebsd.org/pipermail/svn-src-head/2014-March/056833.html -- Ian
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