On 2018年05月09日 10:50, Cong Wang wrote:
On Mon, May 7, 2018 at 11:04 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
On 05/07/2018 10:54 PM, Cong Wang wrote:
Yeah, we should return early before hitting this uninitialized ptr ring...
Something like:
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index ef33950a45d9..638c87a95247 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2128,6 +2128,9 @@ static void *tun_ring_recv(struct tun_file
*tfile, int noblock, int *err)
void *ptr = NULL;
int error = 0;
+ if (!tfile->tx_ring.queue)
+ goto out;
+
Or, checking if tun is detached...
tx_ring was properly initialized when first ptr_ring_consume() at line 2131 was
attempted.
The bug happens later at line 2143 , after a schedule() call, line 2155
So a single check at function prologue wont solve the case the thread had to
sleep,
then some uninit happened.
Very good point. RTNL lock is supposed to protect cleanup path, but I don't
think we can acquire RTNL for tun_chr_read_iter() path...
I think the root cause is we try to initialize ptr ring during TUNSETIFF
since the length depends on the dev->tx_queue_len and try to destroy it
when device is gone. We can solve this by initializing a zero size
ptr_ring during open() and resize if necessary. Then there no need for
any workaround like memset and checking against NULL.
Let me try to cook a patch for this.
Thanks
