| Message ID | 20210416102243.1293871-1-mjt@msgid.tls.msk.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mptsas: remove unused MPTSASState.pending (CVE-2021-3392) | expand |
On 4/16/21 12:22 PM, Michael Tokarev wrote: > During previous attempt to fix CVE-2021-3392 it was discovered > that MPTSASState.pending is actually not used. So instead of > fixing the prob, just remove the offending code entirely What problem? > > Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> > Cc: Prasad J Pandit <pjp@fedoraproject.org> > Cc: qemu-stable@nongnu.org > --- > hw/scsi/mptsas.c | 4 ---- > hw/scsi/mptsas.h | 1 - > 2 files changed, 5 deletions(-) > > diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c > index 7416e78706..5abbc742aa 100644 > --- a/hw/scsi/mptsas.c > +++ b/hw/scsi/mptsas.c > @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) > req->sreq->hba_private = NULL; > scsi_req_unref(req->sreq); > req->sreq = NULL; > - QTAILQ_REMOVE(&s->pending, req, next); > } > qemu_sglist_destroy(&req->qsg); > g_free(req); > @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, > } > > req = g_new0(MPTSASRequest, 1); > - QTAILQ_INSERT_TAIL(&s->pending, req, next); > req->scsi_io = *scsi_io; > req->dev = s; > > @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp) > > s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); > > - QTAILQ_INIT(&s->pending); > - > scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL); > } > > diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h > index b85ac1a5fc..c046497db7 100644 > --- a/hw/scsi/mptsas.h > +++ b/hw/scsi/mptsas.h > @@ -79,7 +79,6 @@ struct MPTSASState { > uint16_t reply_frame_size; > > SCSIBus bus; > - QTAILQ_HEAD(, MPTSASRequest) pending; > }; > > void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req); >
Cc'ing maintainers. On 4/16/21 1:27 PM, Philippe Mathieu-Daudé wrote: > On 4/16/21 12:22 PM, Michael Tokarev wrote: >> During previous attempt to fix CVE-2021-3392 it was discovered >> that MPTSASState.pending is actually not used. So instead of >> fixing the prob, just remove the offending code entirely > > What problem? > >> >> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> >> Cc: Prasad J Pandit <pjp@fedoraproject.org> >> Cc: qemu-stable@nongnu.org >> --- >> hw/scsi/mptsas.c | 4 ---- >> hw/scsi/mptsas.h | 1 - >> 2 files changed, 5 deletions(-) >> >> diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c >> index 7416e78706..5abbc742aa 100644 >> --- a/hw/scsi/mptsas.c >> +++ b/hw/scsi/mptsas.c >> @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) >> req->sreq->hba_private = NULL; >> scsi_req_unref(req->sreq); >> req->sreq = NULL; >> - QTAILQ_REMOVE(&s->pending, req, next); >> } >> qemu_sglist_destroy(&req->qsg); >> g_free(req); >> @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, >> } >> >> req = g_new0(MPTSASRequest, 1); >> - QTAILQ_INSERT_TAIL(&s->pending, req, next); >> req->scsi_io = *scsi_io; >> req->dev = s; >> >> @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp) >> >> s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); >> >> - QTAILQ_INIT(&s->pending); >> - >> scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL); >> } >> >> diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h >> index b85ac1a5fc..c046497db7 100644 >> --- a/hw/scsi/mptsas.h >> +++ b/hw/scsi/mptsas.h >> @@ -79,7 +79,6 @@ struct MPTSASState { >> uint16_t reply_frame_size; >> >> SCSIBus bus; >> - QTAILQ_HEAD(, MPTSASRequest) pending; >> }; >> >> void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req); >> >
On 4/16/21 1:33 PM, Philippe Mathieu-Daudé wrote: > Cc'ing maintainers. > > On 4/16/21 1:27 PM, Philippe Mathieu-Daudé wrote: >> On 4/16/21 12:22 PM, Michael Tokarev wrote: >>> During previous attempt to fix CVE-2021-3392 it was discovered >>> that MPTSASState.pending is actually not used. So instead of >>> fixing the prob, just remove the offending code entirely >> >> What problem? Digging a bit I found: https://bugs.launchpad.net/qemu/+bug/1914236 and Paolo's comment: https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html So your patch now makes sense, but please: 1/ Reword including Prasad description: """ While processing SCSI i/o requests in mptsas_process_scsi_io_request(), the Megaraid emulator appends new MPTSASRequest object 'req' to the 's->pending' queue. In case of an error, this same object gets dequeued in mptsas_free_request() only if SCSIRequest object 'req->sreq' is initialised. This may lead to a use-after-free issue. Since MPTSASState.pending is actually not used, simply remove it. """ 2/ Add: BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392) Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device") With it: Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> >>> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> >>> Cc: Prasad J Pandit <pjp@fedoraproject.org> >>> Cc: qemu-stable@nongnu.org >>> --- >>> hw/scsi/mptsas.c | 4 ---- >>> hw/scsi/mptsas.h | 1 - >>> 2 files changed, 5 deletions(-) >>> >>> diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c >>> index 7416e78706..5abbc742aa 100644 >>> --- a/hw/scsi/mptsas.c >>> +++ b/hw/scsi/mptsas.c >>> @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) >>> req->sreq->hba_private = NULL; >>> scsi_req_unref(req->sreq); >>> req->sreq = NULL; >>> - QTAILQ_REMOVE(&s->pending, req, next); >>> } >>> qemu_sglist_destroy(&req->qsg); >>> g_free(req); >>> @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, >>> } >>> >>> req = g_new0(MPTSASRequest, 1); >>> - QTAILQ_INSERT_TAIL(&s->pending, req, next); >>> req->scsi_io = *scsi_io; >>> req->dev = s; >>> >>> @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp) >>> >>> s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); >>> >>> - QTAILQ_INIT(&s->pending); >>> - >>> scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL); >>> } >>> >>> diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h >>> index b85ac1a5fc..c046497db7 100644 >>> --- a/hw/scsi/mptsas.h >>> +++ b/hw/scsi/mptsas.h >>> @@ -79,7 +79,6 @@ struct MPTSASState { >>> uint16_t reply_frame_size; >>> >>> SCSIBus bus; >>> - QTAILQ_HEAD(, MPTSASRequest) pending; >>> }; >>> >>> void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req); >>> >> >
On 4/18/21 7:14 AM, Philippe Mathieu-Daudé wrote: > On 4/16/21 1:33 PM, Philippe Mathieu-Daudé wrote: >> Cc'ing maintainers. >> >> On 4/16/21 1:27 PM, Philippe Mathieu-Daudé wrote: >>> On 4/16/21 12:22 PM, Michael Tokarev wrote: >>>> During previous attempt to fix CVE-2021-3392 it was discovered >>>> that MPTSASState.pending is actually not used. So instead of >>>> fixing the prob, just remove the offending code entirely >>> >>> What problem? > > Digging a bit I found: > https://bugs.launchpad.net/qemu/+bug/1914236 > and Paolo's comment: > https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg02660.html > > So your patch now makes sense, but please: > > 1/ Reword including Prasad description: > > """ > While processing SCSI i/o requests in mptsas_process_scsi_io_request(), > the Megaraid emulator appends new MPTSASRequest object 'req' to > the 's->pending' queue. In case of an error, this same object gets > dequeued in mptsas_free_request() only if SCSIRequest object > 'req->sreq' is initialised. This may lead to a use-after-free issue. > > Since MPTSASState.pending is actually not used, simply remove it. > """ > > 2/ Add: > > BugLink: https://bugs.launchpad.net/qemu/+bug/1914236 (CVE-2021-3392) > Fixes: e351b826112 ("hw: Add support for LSI SAS1068 (mptsas) device") And: Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr> > With it: > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > >>>> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> >>>> Cc: Prasad J Pandit <pjp@fedoraproject.org> >>>> Cc: qemu-stable@nongnu.org >>>> --- >>>> hw/scsi/mptsas.c | 4 ---- >>>> hw/scsi/mptsas.h | 1 - >>>> 2 files changed, 5 deletions(-)
diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c index 7416e78706..5abbc742aa 100644 --- a/hw/scsi/mptsas.c +++ b/hw/scsi/mptsas.c @@ -257,7 +257,6 @@ static void mptsas_free_request(MPTSASRequest *req) req->sreq->hba_private = NULL; scsi_req_unref(req->sreq); req->sreq = NULL; - QTAILQ_REMOVE(&s->pending, req, next); } qemu_sglist_destroy(&req->qsg); g_free(req); @@ -303,7 +302,6 @@ static int mptsas_process_scsi_io_request(MPTSASState *s, } req = g_new0(MPTSASRequest, 1); - QTAILQ_INSERT_TAIL(&s->pending, req, next); req->scsi_io = *scsi_io; req->dev = s; @@ -1319,8 +1317,6 @@ static void mptsas_scsi_realize(PCIDevice *dev, Error **errp) s->request_bh = qemu_bh_new(mptsas_fetch_requests, s); - QTAILQ_INIT(&s->pending); - scsi_bus_new(&s->bus, sizeof(s->bus), &dev->qdev, &mptsas_scsi_info, NULL); } diff --git a/hw/scsi/mptsas.h b/hw/scsi/mptsas.h index b85ac1a5fc..c046497db7 100644 --- a/hw/scsi/mptsas.h +++ b/hw/scsi/mptsas.h @@ -79,7 +79,6 @@ struct MPTSASState { uint16_t reply_frame_size; SCSIBus bus; - QTAILQ_HEAD(, MPTSASRequest) pending; }; void mptsas_fix_scsi_io_endianness(MPIMsgSCSIIORequest *req);
During previous attempt to fix CVE-2021-3392 it was discovered that MPTSASState.pending is actually not used. So instead of fixing the prob, just remove the offending code entirely Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> Cc: Prasad J Pandit <pjp@fedoraproject.org> Cc: qemu-stable@nongnu.org --- hw/scsi/mptsas.c | 4 ---- hw/scsi/mptsas.h | 1 - 2 files changed, 5 deletions(-)