From: Jia-Ju Bai baijiaju@tsinghua.edu.cn
[ 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 baijiaju@tsinghua.edu.cn Signed-off-by: Sean Young sean@mess.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 f89364951ebdf..fb13cc3c591da 100644 --- a/drivers/media/pci/ttpci/av7110.c +++ b/drivers/media/pci/ttpci/av7110.c @@ -426,14 +426,15 @@ 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,