Commit 6499a0db authored by Jia-Ju Bai's avatar Jia-Ju Bai Committed by Mauro Carvalho Chehab

media: pci: ttpci: av7110: fix possible buffer overflow caused by bad DMA value in debiirq()

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].
Signed-off-by: default avatarJia-Ju Bai <baijiaju@tsinghua.edu.cn>
Signed-off-by: default avatarSean Young <sean@mess.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
parent bc76369b
...@@ -406,14 +406,15 @@ static void debiirq(unsigned long cookie) ...@@ -406,14 +406,15 @@ static void debiirq(unsigned long cookie)
case DATA_CI_GET: case DATA_CI_GET:
{ {
u8 *data = av7110->debi_virt; 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; int flags = 0;
if (data[5] > 0) if (data[5] > 0)
flags |= CA_CI_MODULE_PRESENT; flags |= CA_CI_MODULE_PRESENT;
if (data[5] > 5) if (data[5] > 5)
flags |= CA_CI_MODULE_READY; flags |= CA_CI_MODULE_READY;
av7110->ci_slot[data[0]].flags = flags; av7110->ci_slot[data_0].flags = flags;
} else } else
ci_get_data(&av7110->ci_rbuffer, ci_get_data(&av7110->ci_rbuffer,
av7110->debi_virt, av7110->debi_virt,
......
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