| From 3a664569b71b0a52be5ffb9fb87cc4f83d29bd71 Mon Sep 17 00:00:00 2001 |
| From: Lin Ma <linma@zju.edu.cn> |
| Date: Mon, 28 Nov 2022 16:21:59 +0000 |
| Subject: media: dvbdev: fix refcnt bug |
| |
| From: Lin Ma <linma@zju.edu.cn> |
| |
| commit 3a664569b71b0a52be5ffb9fb87cc4f83d29bd71 upstream. |
| |
| 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> |
| Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> |
| Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| drivers/media/dvb-core/dvbdev.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/media/dvb-core/dvbdev.c |
| +++ b/drivers/media/dvb-core/dvbdev.c |
| @@ -480,8 +480,8 @@ int dvb_register_device(struct dvb_adapt |
| 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; |
