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Subject[Linux-kernel-mentees][PATCH] rtl8150: set memory to all 0xFFs on failed register reads
Date
get_registers() copies whatever memory is written by the
usb_control_msg() call even if the underlying urb call ends up failing.

If get_registers() fails, or ends up reading 0 bytes, meaningless and
junk register values would end up being copied over (and eventually read
by the driver), and since most of the callers of get_registers() don't
check the return values of get_registers() either, this would go unnoticed.

It might be a better idea to try and mirror the PCI master abort
termination and set memory to 0xFFs instead in such cases.

Fixes: https://syzkaller.appspot.com/bug?extid=abbc768b560c84d92fd3
Reported-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com
Tested-by: syzbot+abbc768b560c84d92fd3@syzkaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@gmail.com>
---
drivers/net/usb/rtl8150.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
index 733f120c852b..04fca7bfcbcb 100644
--- a/drivers/net/usb/rtl8150.c
+++ b/drivers/net/usb/rtl8150.c
@@ -162,8 +162,13 @@ static int get_registers(rtl8150_t * dev, u16 indx, u16 size, void *data)
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
RTL8150_REQ_GET_REGS, RTL8150_REQT_READ,
indx, 0, buf, size, 500);
- if (ret > 0 && ret <= size)
+
+ if (ret < 0)
+ memset(data, 0xff, size);
+
+ else
memcpy(data, buf, ret);
+
kfree(buf);
return ret;
}
@@ -276,7 +281,7 @@ static int write_mii_word(rtl8150_t * dev, u8 phy, __u8 indx, u16 reg)

static inline void set_ethernet_addr(rtl8150_t * dev)
{
- u8 node_id[6];
+ u8 node_id[6] = {0};

get_registers(dev, IDR, sizeof(node_id), node_id);
memcpy(dev->netdev->dev_addr, node_id, sizeof(node_id));
--
2.25.1
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