From: Lin Ma <linma@zju.edu.cn>
To: mchehab@kernel.org, linux-media@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Lin Ma <linma@zju.edu.cn>,
syzbot+fce48a3dd3368645bd6c@syzkaller.appspotmail.com
Subject: [PATCH v0] media: dvbdev: fix refcnt bug
Date: Tue, 29 Nov 2022 00:21:59 +0800 [thread overview]
Message-ID: <20221128162159.16901-1-linma@zju.edu.cn> (raw)
Previous commit initialize the dvbdev->ref before the template copy,
which will overwrite the reference and cause refcnt bug.
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.0-rc6-next-20221128-syzkaller #0
...
RIP: 0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25
RSP: 0000:ffffc900000678d0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88813ff58000 RSI: ffffffff81660e7c RDI: fffff5200000cf0c
RBP: ffff888022a45010 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff88823ffff000 CR3: 000000000c48e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_add include/linux/refcount.h:199 [inline]
__refcount_inc include/linux/refcount.h:250 [inline]
refcount_inc include/linux/refcount.h:267 [inline]
kref_get include/linux/kref.h:45 [inline]
dvb_device_get drivers/media/dvb-core/dvbdev.c:585 [inline]
dvb_register_device+0xe83/0x16e0 drivers/media/dvb-core/dvbdev.c:517
...
Just place the kref_init at correct position.
Reported-by: syzbot+fce48a3dd3368645bd6c@syzkaller.appspotmail.com
Fixes: 0fc044b2b5e2 ("media: dvbdev: adopts refcnt to avoid UAF")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
---
drivers/media/dvb-core/dvbdev.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index d45673cb3..2a857cf70 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -482,8 +482,8 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
return -ENOMEM;
}
- kref_init(&dvbdev->ref);
memcpy(dvbdev, template, sizeof(struct dvb_device));
+ kref_init(&dvbdev->ref);
dvbdev->type = type;
dvbdev->id = id;
dvbdev->adapter = adap;
--
2.38.1
reply other threads:[~2022-11-28 16:23 UTC|newest]
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