[Linux-kernel-mentees] [PATCH] ISDN: hfcsusb: checking idx of ep configuration

Phong Tran tranmanphong at gmail.com
Mon Jul 15 15:08:14 UTC 2019


The syzbot test with random endpoint address which made the idx is
overflow in the table of endpoint configuations.

this adds the checking for fixing the error report from
syzbot

KASAN: stack-out-of-bounds Read in hfcsusb_probe [1]
The patch tested by syzbot [2]

Reported-by: syzbot+8750abbc3a46ef47d509 at syzkaller.appspotmail.com

[1]:
https://syzkaller.appspot.com/bug?id=30a04378dac680c5d521304a00a86156bb913522
[2]:
https://groups.google.com/d/msg/syzkaller-bugs/_6HBdge8F3E/OJn7wVNpBAAJ

Signed-off-by: Phong Tran <tranmanphong at gmail.com>
---
 drivers/isdn/hardware/mISDN/hfcsusb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 4c99739b937e..0e224232f746 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -1955,6 +1955,9 @@ hfcsusb_probe(struct usb_interface *intf, const struct usb_device_id *id)
 
 				/* get endpoint base */
 				idx = ((ep_addr & 0x7f) - 1) * 2;
+				if (idx > 15)
+					return -EIO;
+
 				if (ep_addr & 0x80)
 					idx++;
 				attr = ep->desc.bmAttributes;
-- 
2.11.0



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