On Thu, Aug 16, 2018 at 05:23:26PM -0600, Warner Losh wrote: > On Thu, Aug 16, 2018 at 5:16 PM, Brooks Davis <bro...@freebsd.org> wrote: > > > On Fri, Aug 17, 2018 at 07:04:05AM +0800, Marcelo Araujo wrote: > > > 2018-08-17 3:29 GMT+08:00 Rodney W. Grimes <free...@pdx.rh.cn85.dnsmgr. > > net>: > > > > > > > > On Thu, Aug 16, 2018 at 11:06 AM, John-Mark Gurney <j...@funkthat.com > > > > > > > wrote: > > > > > > > > > > > Marcelo Araujo wrote this message on Thu, Aug 16, 2018 at 06:31 > > +0000: > > > > > > > Author: araujo > > > > > > > Date: Thu Aug 16 06:31:54 2018 > > > > > > > New Revision: 337887 > > > > > > > URL: https://svnweb.freebsd.org/changeset/base/337887 > > > > > > > > > > > > > > Log: > > > > > > > Add a comment explaining how the PSN works and why there is no > > > > need for > > > > > > > a null terminator. Also mark CID 1394825 as intentional. > > > > > > > > > > > > > > Reported by: Coverity > > > > > > > CID: 1394825 > > > > > > > MFC after: 1 week > > > > > > > Sponsored by: iXsystems Inc. > > > > > > > > > > > > > > Modified: > > > > > > > head/usr.sbin/bhyve/pci_nvme.c > > > > > > > > > > > > > > Modified: head/usr.sbin/bhyve/pci_nvme.c > > > > > > > ============================================================ > > > > > > ================== > > > > > > > --- head/usr.sbin/bhyve/pci_nvme.c Thu Aug 16 06:20:25 2018 > > > > > > (r337886) > > > > > > > +++ head/usr.sbin/bhyve/pci_nvme.c Thu Aug 16 06:31:54 2018 > > > > > > (r337887) > > > > > > > @@ -1714,6 +1714,11 @@ pci_nvme_parse_opts(struct pci_nvme_softc > > *sc, > > > > > > char *o > > > > > > > > > > > > [...] > > > > > > > > > > > > > memset(sc->ctrldata.sn, 0, sizeof(sc-> > > > > ctrldata.sn > > > > > > )); > > > > > > > strncpy(sc->ctrldata.sn, config, > > > > > > > sizeof(sc->ctrldata.sn)); > > > > > > > > > > > > This memset is unneeded, as strncpy will write NUL bytes to fill > > out > > > > > > the buffer: > > > > > > If src is less than len characters long, the remainder of > > > > > > dst is filled with `\0' characters. > > > > > > > > > > > > > > > > It also looks like the comment was wrong. The newest NVMe standards > > say > > > > > these fields should be 7-bit and space-padded. > > > > > > > > lol, which is what the vendor that caused me grief with > > > > ata serial numbers did decades ago. > > > > > > > > -- > > > > Rod Grimes > > > > rgri...@freebsd.org > > > > > > > > > > I have discussed a bit with imp@, but I will drop the patch here to get > > > other peoples opinion too. > > > So, name space and firmware number also need to be padded with spaces. > > > > > > I couldn't think in any other better way to do that. > > > > > > Does this patch looks reasonable? > > > https://people.freebsd.org/~araujo/pci_nvme.diff > > > > You should check that len<=dst_size and at least truncate rather than > > overflowing. If the strings from userspace you need to return or log an > > error, if they come from the kernel, you can panic. > > Help me understand, I thought that the strnlen bounded what was copied.
Apparently the standard calls for ' ' rather than '\0' padding. The prop memcpy+memset does the job, but contains potential overflows. -- Brooks
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