[PATCH 5.4 138/411] media: pvrusb2: fix array-index-out-of-bounds in pvr2_i2c_core_init

Greg Kroah-Hartman
2022-06-13T11:20:26Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ Upstream commit 471bec68457aaf981add77b4f590d65dd7da1059 ]

Syzbot reported that -1 is used as array index. The problem was in
missing validation check.

hdw->unit_number is initialized with -1 and then if init table walk fails
this value remains unchanged. Since code blindly uses this member for
array indexing adding sanity check is the easiest fix for that.

hdw->workpoll initialization moved upper to prevent warning in
__flush_work.

Reported-and-tested-by: syzbot+1a247e36149ffd709a9b@syzkaller.appspotmail.com

Fixes: d855497edbfb ("V4L/DVB (4228a): pvrusb2 to kernel 2.6.18")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/usb/pvrusb2/pvrusb2-hdw.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
index 2f00679f65a0..11e7fcfc3f19 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
@@ -2570,6 +2570,11 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,
} while (0);
mutex_unlock(&pvr2_unit_mtx);

+ INIT_WORK(&hdw->workpoll, pvr2_hdw_worker_poll);
+
+ if (hdw->unit_number == -1)
+ goto fail;
+
cnt1 = 0;
cnt2 = scnprintf(hdw->name+cnt1,sizeof(hdw->name)-cnt1,"pvrusb2");
cnt1 += cnt2;
@@ -2581,8 +2586,6 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,
if (cnt1 >= sizeof(hdw->name)) cnt1 = sizeof(hdw->name)-1;
hdw->name[cnt1] = 0;

- INIT_WORK(&hdw->workpoll,pvr2_hdw_worker_poll);
-
pvr2_trace(PVR2_TRACE_INIT,"Driver unit number is %d, name is %s",
hdw->unit_number,hdw->name);

--
2.35.1