From: =?UTF-8?Q?Martin_MOKREJ=c5=a0?= Subject: Re: 4.5.1: UBSAN: Undefined behaviour in ./arch/x86/include/asm/atomic.h:156:9 Date: Thu, 21 Apr 2016 13:17:19 +0200 Message-ID: <2121831c-e066-bb83-3b66-d3d3907064bf@gmail.com> References: <7d648a97-38f5-3d04-9ead-0b6e87088beb@gmail.com> <20160421004229.GB10917@kroah.com> <56e89573-3fb5-39cc-c330-e6f1c1c6c58f@gmail.com> <20160421104800.GA6884@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: USB list , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Greg KH Return-path: In-Reply-To: <20160421104800.GA6884-U8xfFu+wG4EAvxtiuMwx3w@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-ext4.vger.kernel.org Greg KH wrote: > On Thu, Apr 21, 2016 at 11:18:16AM +0200, Martin MOKREJ=C5=A0 wrote: >> Hi Greg, >> >> thank you for your answer. >> >> Greg KH wrote: >>> On Thu, Apr 21, 2016 at 12:22:49AM +0200, Martin MOKREJ=C5=A0 wrote= : >>>> Hi, >>>> I am not certain to to forward this to, so I am trying linux-usb= and ext4. Please add relevant people/lists, thank you. >>>> >>>> # dmesg | grep "UBSAN: Undefined behaviour" >>>> [ 2.638843] UBSAN: Undefined behaviour in drivers/usb/host/ehci= -hub.c:873:47 >>>> [ 8.553620] UBSAN: Undefined behaviour in fs/ext4/mballoc.c:261= 2:15 >>>> [ 25.341048] UBSAN: Undefined behaviour in fs/ext4/mballoc.c:127= 4:11 >>>> [ 41.460542] UBSAN: Undefined behaviour in ./arch/x86/include/as= m/atomic.h:156:9 >>>> # >>>> >>>> Full dmesg is attached. >>>> >>>> Hope this helps, >>>> Martin >>> >>>> [ 0.000000] Linux version 4.5.1-default-pciehp (root@vostro) (g= cc version 5.3.0 (Gentoo 5.3.0 p1.0, pie-0.6.5) ) #1 SMP Thu Apr 14 14:= 17:48 CEST 2016 >>> >>> Please try 4.6-rc4, a number of UBSAN issues have been fixed there. >> >> They are still present: >> >> # dmesg | grep "UBSAN: Undefined behaviour" >> [ 3.113405] UBSAN: Undefined behaviour in drivers/usb/host/ehci-h= ub.c:877:47 >> [ 5.678949] UBSAN: Undefined behaviour in fs/ext4/mballoc.c:2619:= 15 >> [ 18.345599] UBSAN: Undefined behaviour in fs/ext4/mballoc.c:1281:= 11 >> [ 34.544363] UBSAN: Undefined behaviour in ./arch/x86/include/asm/= atomic.h:156:9 > > Ah, sorry about that, turns out this is a bug in the tool, not in the > code, see the thread from a few weeks ago in the linux-usb archives w= ith > the subject: > Subject: function ehci_hub_control in ehci-hub.c > for all of the details. Thank you. I am not a programmer so I only infer from this thread I sho= uld disable the UBSAN in .config. The kernel code is technically correct but trigge= rs false alarm. Maybe the UBSAN could have a whitelist of falsely matching locations? https://www.mail-archive.com/linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg72438.html Did anybody check the ext4 code or is it also just believed the UBSAN c= omplaint is just broken and code changes are not necessary? Martin -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html