| Message ID | 20181206121830.6177-1-ppandit@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] i2c: pm_smbus: check smb_index before block transfer write | expand |
On 12/6/18 1:18 PM, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While performing block transfer write in smb_ioport_writeb(), > 'smb_index' is incremented and used to index smb_data[] array. > Check 'smb_index' value to avoid OOB access. > > Note that this bug is exploitable by a guest to escape > from the virtual machine. However the commit which > introduced the bug was only made after the 3.0 release, > and so it is not present in any released QEMU versions. > > Fixes: 38ad4fae43 i2c: pm_smbus: Add block transfer capability > Reported-by: Michael Hanselmann <public@hansmi.ch> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> > --- > hw/i2c/pm_smbus.c | 3 +++ > 1 file changed, 3 insertions(+) > > Update v1: add note about issue being introduced after 3.0 release > -> https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01115.html > > diff --git a/hw/i2c/pm_smbus.c b/hw/i2c/pm_smbus.c > index 685a2378ed..03062740cc 100644 > --- a/hw/i2c/pm_smbus.c > +++ b/hw/i2c/pm_smbus.c > @@ -240,6 +240,9 @@ static void smb_ioport_writeb(void *opaque, hwaddr addr, uint64_t val, > uint8_t read = s->smb_addr & 0x01; > > s->smb_index++; > + if (s->smb_index >= PM_SMBUS_MAX_MSG_SIZE) { > + s->smb_index = 0; > + } > if (!read && s->smb_index == s->smb_data0) { > uint8_t prot = (s->smb_ctl >> 2) & 0x07; > uint8_t cmd = s->smb_cmd; >
On Thu, Dec 06, 2018 at 05:48:30PM +0530, P J P wrote: > From: Prasad J Pandit <pjp@fedoraproject.org> > > While performing block transfer write in smb_ioport_writeb(), > 'smb_index' is incremented and used to index smb_data[] array. > Check 'smb_index' value to avoid OOB access. > > Note that this bug is exploitable by a guest to escape > from the virtual machine. However the commit which > introduced the bug was only made after the 3.0 release, > and so it is not present in any released QEMU versions. > > Fixes: 38ad4fae43 i2c: pm_smbus: Add block transfer capability > Reported-by: Michael Hanselmann <public@hansmi.ch> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> > --- > hw/i2c/pm_smbus.c | 3 +++ > 1 file changed, 3 insertions(+) > > Update v1: add note about issue being introduced after 3.0 release > -> https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01115.html > > diff --git a/hw/i2c/pm_smbus.c b/hw/i2c/pm_smbus.c > index 685a2378ed..03062740cc 100644 > --- a/hw/i2c/pm_smbus.c > +++ b/hw/i2c/pm_smbus.c > @@ -240,6 +240,9 @@ static void smb_ioport_writeb(void *opaque, hwaddr addr, uint64_t val, > uint8_t read = s->smb_addr & 0x01; > > s->smb_index++; > + if (s->smb_index >= PM_SMBUS_MAX_MSG_SIZE) { > + s->smb_index = 0; > + } when I see patterns like these I always think "what about spectre". But not a new issue and not the only place, so we can leave this for another day. > if (!read && s->smb_index == s->smb_data0) { > uint8_t prot = (s->smb_ctl >> 2) & 0x07; > uint8_t cmd = s->smb_cmd; > -- > 2.19.2
On Thu, 6 Dec 2018 at 12:20, P J P <ppandit@redhat.com> wrote: > > From: Prasad J Pandit <pjp@fedoraproject.org> > > While performing block transfer write in smb_ioport_writeb(), > 'smb_index' is incremented and used to index smb_data[] array. > Check 'smb_index' value to avoid OOB access. > > Note that this bug is exploitable by a guest to escape > from the virtual machine. However the commit which > introduced the bug was only made after the 3.0 release, > and so it is not present in any released QEMU versions. > > Fixes: 38ad4fae43 i2c: pm_smbus: Add block transfer capability > Reported-by: Michael Hanselmann <public@hansmi.ch> > Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> > --- > hw/i2c/pm_smbus.c | 3 +++ > 1 file changed, 3 insertions(+) > > Update v1: add note about issue being introduced after 3.0 release > -> https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg01115.html Applied, thanks. -- PMM
diff --git a/hw/i2c/pm_smbus.c b/hw/i2c/pm_smbus.c index 685a2378ed..03062740cc 100644 --- a/hw/i2c/pm_smbus.c +++ b/hw/i2c/pm_smbus.c @@ -240,6 +240,9 @@ static void smb_ioport_writeb(void *opaque, hwaddr addr, uint64_t val, uint8_t read = s->smb_addr & 0x01; s->smb_index++; + if (s->smb_index >= PM_SMBUS_MAX_MSG_SIZE) { + s->smb_index = 0; + } if (!read && s->smb_index == s->smb_data0) { uint8_t prot = (s->smb_ctl >> 2) & 0x07; uint8_t cmd = s->smb_cmd;