Re: PROBLEM: tun/tap crashes if open() /dev/net/tun and then poll() it.

Re: PROBLEM: tun/tap crashes if open() /dev/net/tun and then poll() it.

[Herbert Xu]

On Mon, Jul 06, 2009 at 12:11:14AM +0200, Mariusz Kozlowski wrote:
>
> 	Can you try this patch?
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 11a0ba4..c599327 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -486,12 +486,14 @@ static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
>  {
>  	struct tun_file *tfile = file->private_data;
>  	struct tun_struct *tun = __tun_get(tfile);
> -	struct sock *sk = tun->sk;
> +	struct sock *sk;
>  	unsigned int mask = 0;
>  
>  	if (!tun)
>  		return POLLERR;
>  
> +	sk = tun->sk;
> +
>  	DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);
>  
>  	poll_wait(file, &tun->socket.wait, wait);

Good catch.  Can you please resend with a sign-off?

Thanks,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
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Re: PROBLEM: tun/tap crashes if open() /dev/net/tun and then poll() it.

[Mariusz Kozlowski]

On Mon, 6 Jul 2009 09:12:30 +0800
Herbert Xu <herbert@gondor.apana.org.au> wrote:

> On Mon, Jul 06, 2009 at 12:11:14AM +0200, Mariusz Kozlowski wrote:
> >
> > 	Can you try this patch?
... 
> Good catch.  Can you please resend with a sign-off?

Sure. Just wanted to wait for confirmation from Eugene.

Fix NULL pointer dereference in tun_chr_pool() introduced by
commit 33dccbb050bbe35b88ca8cf1228dcf3e4d4b3554 and triggered
by this code:

	int fd;
	struct pollfd pfd;
	fd = open("/dev/net/tun", O_RDWR);
	pfd.fd = fd;
	pfd.events = POLLIN | POLLOUT;
	poll(&pfd, 1, 0);

Reported-by: Eugene Kapun <abacabadabacaba@gmail.com>
Signed-off-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a1b0697..bcbb25e 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -482,12 +482,14 @@ static unsigned int tun_chr_poll(struct file *file, poll_table * wait)
 {
 	struct tun_file *tfile = file->private_data;
 	struct tun_struct *tun = __tun_get(tfile);
-	struct sock *sk = tun->sk;
+	struct sock *sk;
 	unsigned int mask = 0;
 
 	if (!tun)
 		return POLLERR;
 
+	sk = tun->sk;
+
 	DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);
 
 	poll_wait(file, &tfile->read_wait, wait);

Re: PROBLEM: tun/tap crashes if open() /dev/net/tun and then poll() it.

[David Miller]

From: Mariusz Kozlowski <m.kozlowski@tuxland.pl>
Date: Mon, 6 Jul 2009 07:48:35 +0200

> Fix NULL pointer dereference in tun_chr_pool() introduced by
> commit 33dccbb050bbe35b88ca8cf1228dcf3e4d4b3554 and triggered
> by this code:
> 
> 	int fd;
> 	struct pollfd pfd;
> 	fd = open("/dev/net/tun", O_RDWR);
> 	pfd.fd = fd;
> 	pfd.events = POLLIN | POLLOUT;
> 	poll(&pfd, 1, 0);
> 
> Reported-by: Eugene Kapun <abacabadabacaba@gmail.com>
> Signed-off-by: Mariusz Kozlowski <m.kozlowski@tuxland.pl>

Applied, thanks!