From: sumitg <sumitg@xxxxxxxxxx>
Fixing use-after-free within __v4l2_ctrl_handler_setup().
Memory is being freed with kfree(new_ref) for duplicate
control reference entry but cluster is still referring
to the duplicate entry. Change done to point cluster to
original reference instead of duplicate which is freed.
==================================================================
BUG: KASAN: use-after-free in __v4l2_ctrl_handler_setup+0x388/0x428
Read of size 8 at addr ffffffc324e78618 by task systemd-udevd/312
Allocated by task 312:
Freed by task 312:
The buggy address belongs to the object at ffffffc324e78600
which belongs to the cache kmalloc-64 of size 64
The buggy address is located 24 bytes inside of
64-byte region [ffffffc324e78600, ffffffc324e78640)
The buggy address belongs to the page:
page:ffffffbf0c939e00 count:1 mapcount:0 mapping:
(null) index:0xffffffc324e78f80
flags: 0x4000000000000100(slab)
raw: 4000000000000100 0000000000000000 ffffffc324e78f80 000000018020001a
raw: 0000000000000000 0000000100000001 ffffffc37040fb80 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffffffc324e78500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffffffc324e78580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffffffc324e78600: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
^
ffffffc324e78680: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
ffffffc324e78700: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
==================================================================
Signed-off-by: sumitg <sumitg@xxxxxxxxxx>
---
drivers/media/v4l2-core/v4l2-ctrls.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 5e3806f..e971bab 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -2182,6 +2182,7 @@ static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
continue;
/* Don't add duplicates */
if (ref->ctrl->id == id) {
+ ctrl->cluster = &ref->ctrl;
kfree(new_ref);
goto unlock;
}
--
2.7.4
