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

drivers/media/pci/ttpci/av7110.c

+3 −2
Original line number Diff line number Diff line
@@ -406,14 +406,15 @@ 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,