| Message ID | 20221128162159.16901-1-linma@zju.edu.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v0] media: dvbdev: fix refcnt bug | expand |
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;
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(-)