From: Sumit Gupta <sumitg@nvidia.com>
To: <mchehab@kernel.org>, <hverkuil-cisco@xs4all.nl>,
<sakari.ailus@linux.intel.com>, <paul.kocialkowski@bootlin.com>,
<tfiga@chromium.org>, <keiichiw@chromium.org>,
<sumitg@nvidia.com>
Cc: <linux-media@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: [PATCH] [media] v4l2-core: fix use-after-free error
Date: Wed, 10 Apr 2019 19:58:28 +0530 [thread overview]
Message-ID: <1554906508-17192-1-git-send-email-sumitg@nvidia.com> (raw)
From: sumitg <sumitg@nvidia.com>
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@nvidia.com>
---
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
next reply other threads:[~2019-04-10 14:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-10 14:28 Sumit Gupta [this message]
2019-04-10 14:52 ` [PATCH] [media] v4l2-core: fix use-after-free error Hans Verkuil
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