Greg, On Tue, Sep 01, 2020 at 05:09:31PM +0200, Greg Kroah-Hartman wrote: > From: Jia-Ju Bai <baijiaju@xxxxxxxxxxxxxxx> > > [ Upstream commit 6499a0db9b0f1e903d52f8244eacc1d4be00eea2 ] > > The value av7110->debi_virt is stored in DMA memory, and it is assigned > to data, and thus data[0] can be modified at any time by malicious > hardware. In this case, "if (data[0] < 2)" can be passed, but then > data[0] can be changed into a large number, which may cause buffer > overflow when the code "av7110->ci_slot[data[0]]" is used. > > To fix this possible bug, data[0] is assigned to a local variable, which > replaces the use of data[0]. See the discussion here: https://lkml.org/lkml/2020/8/31/479 It does not seem worthwhile merging to the stable trees. Thanks Sean > > Signed-off-by: Jia-Ju Bai <baijiaju@xxxxxxxxxxxxxxx> > Signed-off-by: Sean Young <sean@xxxxxxxx> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > --- > drivers/media/pci/ttpci/av7110.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/drivers/media/pci/ttpci/av7110.c b/drivers/media/pci/ttpci/av7110.c > index d6816effb8786..d02b5fd940c12 100644 > --- a/drivers/media/pci/ttpci/av7110.c > +++ b/drivers/media/pci/ttpci/av7110.c > @@ -424,14 +424,15 @@ static void debiirq(unsigned long cookie) > case DATA_CI_GET: > { > u8 *data = av7110->debi_virt; > + u8 data_0 = data[0]; > > - if ((data[0] < 2) && data[2] == 0xff) { > + if (data_0 < 2 && data[2] == 0xff) { > int flags = 0; > if (data[5] > 0) > flags |= CA_CI_MODULE_PRESENT; > if (data[5] > 5) > flags |= CA_CI_MODULE_READY; > - av7110->ci_slot[data[0]].flags = flags; > + av7110->ci_slot[data_0].flags = flags; > } else > ci_get_data(&av7110->ci_rbuffer, > av7110->debi_virt, > -- > 2.25.1 > >
