From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: Re: [PATCH 2/2] ax25: add refcount in ax25_dev to avoid UAF bugs Date: Mon, 31 Jan 2022 16:22:41 +0300 Message-ID: <20220131132241.GK1951@kadam> References: <855641b37699b6ff501c4bae8370d26f59da9c81.1643343397.git.duoming@zju.edu.cn> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : content-type : in-reply-to : mime-version; s=corp-2021-07-09; bh=7VTflFPpvvIjoJRuq+gGxX9hfCZ5qUNQtmWor8yG0A4=; b=asy47KY1xTWjwfW/2prLV6FrQaehO0TUhvJf7Jfrby42kVs5R8u1XuNiop2Kp9UZPPdF ZCG6j/Ro/3YEsNzvGG7yoBRLQqtWmeiXuHmNPkZUayQtMIZfzoHZxR/ADFB+87bE3unB 9of+tNXPUdnEYWrtYZAvpIX1hCAaXQ72QQXVGKiRmPWp1A7N2XUXlvNScBfxSRhlTVFL oV6SN+KScFLf8HoCptExii13wabGdjZwI9B1FDtHX3EPJKy8DdLDvE2Kal8IYVyFD3xO q4P0I+u/OHrKZ7NjGiZ0BwA1dWHfOp9lpXPTzOHjjejZdZGhInyucZs8kTNXr822zfRv Kw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=7VTflFPpvvIjoJRuq+gGxX9hfCZ5qUNQtmWor8yG0A4=; b=ZeDUmwEpCpDZ6/yNIln5JuG/XPcto9MlrFodWDeKBaxs7vTNvy3wGcibH+LEGgRgdzNadpq7TkVYyYnuLrJJ2IlsG5v8htHxUBxYtKKNZpRBDpP2JyeC9ZhOo2ozlxOV6BSa9ss+6jS/7qEifJlKLOH09iLVYYFpQf197qMICFQ= Content-Disposition: inline In-Reply-To: <855641b37699b6ff501c4bae8370d26f59da9c81.1643343397.git.duoming@zju.edu.cn> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Duoming Zhou Cc: linux-hams@vger.kernel.org, jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org On Fri, Jan 28, 2022 at 12:47:16PM +0800, Duoming Zhou wrote: > diff --git a/include/net/ax25.h b/include/net/ax25.h > index 526e4958919..50b417df622 100644 > --- a/include/net/ax25.h > +++ b/include/net/ax25.h > @@ -239,6 +239,7 @@ typedef struct ax25_dev { > #if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER) > ax25_dama_info dama; > #endif > + refcount_t refcount; > } ax25_dev; > > typedef struct ax25_cb { > @@ -293,6 +294,15 @@ static __inline__ void ax25_cb_put(ax25_cb *ax25) > } > } > > +#define ax25_dev_hold(__ax25_dev) \ > + refcount_inc(&((__ax25_dev)->refcount)) Make this an inline function. > + > +static __inline__ void ax25_dev_put(ax25_dev *ax25_dev) Please run checkpatch.pl --strict on your patches. s/__inline__/inline/ > +{ > + if (refcount_dec_and_test(&ax25_dev->refcount)) { > + kfree(ax25_dev); > + } Delete the extra curly braces. > +} > static inline __be16 ax25_type_trans(struct sk_buff *skb, struct net_device *dev) > { > skb->dev = dev; > diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c > index 44a8730c26a..32f61978ff2 100644 > --- a/net/ax25/af_ax25.c > +++ b/net/ax25/af_ax25.c > @@ -91,6 +91,7 @@ static void ax25_kill_by_device(struct net_device *dev) > spin_unlock_bh(&ax25_list_lock); > lock_sock(sk); > s->ax25_dev = NULL; > + ax25_dev_put(ax25_dev); > release_sock(sk); > ax25_disconnect(s, ENETUNREACH); > spin_lock_bh(&ax25_list_lock); > @@ -439,6 +440,7 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg) > } > > out_put: > + ax25_dev_put(ax25_dev); The ax25_ctl_ioctl() has a ton of reference leak paths now. Almost every return -ESOMETHING needs to be fixed. > ax25_cb_put(ax25); > return ret; > > diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c > index 256fadb94df..770b787fb7b 100644 > --- a/net/ax25/ax25_dev.c > +++ b/net/ax25/ax25_dev.c > @@ -37,6 +37,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr) > for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next) > if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) { > res = ax25_dev; > + ax25_dev_hold(ax25_dev); > } > spin_unlock_bh(&ax25_dev_lock); > > @@ -56,6 +57,7 @@ void ax25_dev_device_up(struct net_device *dev) > return; > } > > + refcount_set(&ax25_dev->refcount, 1); > dev->ax25_ptr = ax25_dev; > ax25_dev->dev = dev; > dev_hold_track(dev, &ax25_dev->dev_tracker, GFP_ATOMIC); > @@ -83,6 +85,7 @@ void ax25_dev_device_up(struct net_device *dev) > spin_lock_bh(&ax25_dev_lock); > ax25_dev->next = ax25_dev_list; > ax25_dev_list = ax25_dev; > + ax25_dev_hold(ax25_dev); > spin_unlock_bh(&ax25_dev_lock); > > ax25_register_dev_sysctl(ax25_dev); > @@ -112,20 +115,22 @@ void ax25_dev_device_down(struct net_device *dev) > > if ((s = ax25_dev_list) == ax25_dev) { > ax25_dev_list = s->next; > + ax25_dev_put(ax25_dev); Do we not have to call ax25_dev_hold(s->next)? > spin_unlock_bh(&ax25_dev_lock); > dev->ax25_ptr = NULL; > dev_put_track(dev, &ax25_dev->dev_tracker); > - kfree(ax25_dev); > + ax25_dev_put(ax25_dev); > return; > } > > while (s != NULL && s->next != NULL) { > if (s->next == ax25_dev) { > s->next = ax25_dev->next; > + ax25_dev_put(ax25_dev); ax25_dev_hold(ax25_dev->next)? > spin_unlock_bh(&ax25_dev_lock); > dev->ax25_ptr = NULL; > dev_put_track(dev, &ax25_dev->dev_tracker); > - kfree(ax25_dev); > + ax25_dev_put(ax25_dev); > return; > } > > @@ -133,6 +138,7 @@ void ax25_dev_device_down(struct net_device *dev) > } > spin_unlock_bh(&ax25_dev_lock); > dev->ax25_ptr = NULL; > + ax25_dev_put(ax25_dev); > } > > int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd) > @@ -149,6 +155,7 @@ int ax25_fwd_ioctl(unsigned int cmd, struct ax25_fwd_struct *fwd) > if (ax25_dev->forward != NULL) > return -EINVAL; Every return -ERROR; in this function leaks reference counts. This one should drop the reference for both fwd_dev and ax25_dev. > ax25_dev->forward = fwd_dev->dev; > + ax25_dev_put(fwd_dev); > break; > > case SIOCAX25DELFWD: regards, dan carpenter