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From 354dd3924a2e43806774953de536257548b5002c Mon Sep 17 00:00:00 2001
From: Steven Toth <stoth@kernellabs.com>
Date: Tue, 6 Jun 2017 08:30:27 -0400
Subject: [PATCH] [PATCH] saa7164: Bug - Double fetch PCIe access condition
Avoid a double fetch by reusing the values from the prior transfer.
Originally reported via https://bugzilla.kernel.org/show_bug.cgi?id=195559
Thanks to Pengfei Wang <wpengfeinudt@gmail.com> for reporting.
CVE: CVE-2017-8831
Upstream-Status: Backport [backport from ...
Signed-off-by: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
drivers/media/pci/saa7164/saa7164-bus.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
diff --git a/drivers/media/pci/saa7164/saa7164-bus.c b/drivers/media/pci/saa7164/saa7164-bus.c
index b2ff82fa7116..ecfeac5cdbed 100644
--- a/drivers/media/pci/saa7164/saa7164-bus.c
+++ b/drivers/media/pci/saa7164/saa7164-bus.c
@@ -389,11 +389,11 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
msg_tmp.size = le16_to_cpu((__force __le16)msg_tmp.size);
msg_tmp.command = le32_to_cpu((__force __le32)msg_tmp.command);
msg_tmp.controlselector = le16_to_cpu((__force __le16)msg_tmp.controlselector);
+ memcpy(msg, &msg_tmp, sizeof(*msg));
/* No need to update the read positions, because this was a peek */
/* If the caller specifically want to peek, return */
if (peekonly) {
- memcpy(msg, &msg_tmp, sizeof(*msg));
goto peekout;
}
@@ -438,21 +438,15 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
space_rem = bus->m_dwSizeGetRing - curr_grp;
if (space_rem < sizeof(*msg)) {
- /* msg wraps around the ring */
- memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, space_rem);
- memcpy_fromio((u8 *)msg + space_rem, bus->m_pdwGetRing,
- sizeof(*msg) - space_rem);
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing + sizeof(*msg) -
space_rem, buf_size);
} else if (space_rem == sizeof(*msg)) {
- memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing, buf_size);
} else {
/* Additional data wraps around the ring */
- memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf) {
memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp +
sizeof(*msg), space_rem - sizeof(*msg));
@@ -465,15 +459,10 @@ int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
} else {
/* No wrapping */
- memcpy_fromio(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
if (buf)
memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp + sizeof(*msg),
buf_size);
}
- /* Convert from little endian to CPU */
- msg->size = le16_to_cpu((__force __le16)msg->size);
- msg->command = le32_to_cpu((__force __le32)msg->command);
- msg->controlselector = le16_to_cpu((__force __le16)msg->controlselector);
/* Update the read positions, adjusting the ring */
saa7164_writel(bus->m_dwGetReadPos, new_grp);
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