Date: Sun, 16 May 2021 12:27:44 -0500 From: Warner Losh <imp@bsdimp.com> To: Mark Johnston <markj@freebsd.org> Cc: Edward Tomasz Napierala <trasz@freebsd.org>, src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org Subject: Re: git: 0f206cc91279 - main - cam: add missing zeroing of a stack-allocated CCB. Message-ID: <CANCZdfrPuWJeH4xK6Z0E1c2s6fvn5_tcwd0wN%2Bs7R-aKD61zqQ@mail.gmail.com> In-Reply-To: <YKFOeDlJhm8sJHJX@nuc> References: <202105161045.14GAjZIL093217@gitrepo.freebsd.org> <YKFOeDlJhm8sJHJX@nuc>
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On Sun, May 16, 2021, 11:55 AM Mark Johnston <markj@freebsd.org> wrote: > On Sun, May 16, 2021 at 10:45:35AM +0000, Edward Tomasz Napierala wrote: > > The branch main has been updated by trasz: > > > > URL: > https://cgit.FreeBSD.org/src/commit/?id=0f206cc91279e630ad9e733eb6e330b7dbe6c70e > > > > commit 0f206cc91279e630ad9e733eb6e330b7dbe6c70e > > Author: Edward Tomasz Napierala <trasz@FreeBSD.org> > > AuthorDate: 2021-05-16 09:28:04 +0000 > > Commit: Edward Tomasz Napierala <trasz@FreeBSD.org> > > CommitDate: 2021-05-16 10:38:26 +0000 > > > > cam: add missing zeroing of a stack-allocated CCB. > > > > This could cause a panic at boot. > > There are other instances of this, for example syzbot is currently > hitting an assertion, seemingly because the alloc_flags field of a > stack-allocated CCB was not zeroed: > https://syzkaller.appspot.com/bug?extid=2e9ce63919709feb3d1c > > I think the patch below will fix it, but I did not audit other callers. > It feels a bit strange to require all callers of xpt_setup_ccb() to > manually zero the structure first, can we provide a single routine to > initialize stack-allocated CCBs? > If we did, we could set a flag we could assert on, and/or do static analysis to find any others... Warner diff --git a/sys/dev/virtio/scsi/virtio_scsi.c > b/sys/dev/virtio/scsi/virtio_scsi.c > index 51d9e5f532f7..adf4fd17fc5b 100644 > --- a/sys/dev/virtio/scsi/virtio_scsi.c > +++ b/sys/dev/virtio/scsi/virtio_scsi.c > @@ -700,6 +700,7 @@ vtscsi_register_async(struct vtscsi_softc *sc) > { > struct ccb_setasync csa; > > + memset(&csa, 0, sizeof(csa)); > xpt_setup_ccb(&csa.ccb_h, sc->vtscsi_path, 5); > csa.ccb_h.func_code = XPT_SASYNC_CB; > csa.event_enable = AC_LOST_DEVICE | AC_FOUND_DEVICE; > @@ -716,6 +717,7 @@ vtscsi_deregister_async(struct vtscsi_softc *sc) > { > struct ccb_setasync csa; > > + memset(&csa, 0, sizeof(csa)); > xpt_setup_ccb(&csa.ccb_h, sc->vtscsi_path, 5); > csa.ccb_h.func_code = XPT_SASYNC_CB; > csa.event_enable = 0; >
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