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

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Fix NULL pointer dereference in tun_chr_pool() introduced by commit
33dccbb050 ("tun: Limit amount of queued
packets per device") 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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mariusz Kozlowski 2009-07-05 19:48:35 +00:00 committed by David S. Miller
parent 1ded3f59f3
commit 3c8a9c63d5
1 changed files with 3 additions and 1 deletions
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4
drivers/net/tun.c
View file

@ -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);