From 5c043e7826d838ce833cab47c8b2e95ac92dc36a Mon Sep 17 00:00:00 2001 From: Jia-Ju Bai Date: Sat, 30 May 2020 16:42:08 +0200 Subject: [PATCH] media: pci: ttpci: av7110: fix possible buffer overflow caused by bad DMA value in debiirq() [ 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]. Signed-off-by: Jia-Ju Bai Signed-off-by: Sean Young Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- 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 f46947d8adf8..fcc053d95ae4 100644 --- a/drivers/media/pci/ttpci/av7110.c +++ b/drivers/media/pci/ttpci/av7110.c @@ -423,14 +423,15 @@ 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, -- 2.20.1