[PATCH 1/2][INET] Fix potential kfree on vmalloc-ed area of request_sock_queue

[PATCH 1/2][INET] Fix potential kfree on vmalloc-ed area of request_sock_queue

[Pavel Emelyanov]

The request_sock_queue's listen_opt is either vmalloc-ed or
kmalloc-ed depending on the number of table entries. Thus it 
is expected to be handled properly on free, which is done in 
the reqsk_queue_destroy().

However the error path in inet_csk_listen_start() calls 
the lite version of reqsk_queue_destroy, called 
__reqsk_queue_destroy, which calls the kfree unconditionally. 

Fix this and move the __reqsk_queue_destroy into a .c file as 
it looks too big to be inline.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>

---

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 7aed02c..0a954ee 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -136,11 +136,7 @@ static inline struct listen_sock *reqsk_queue_yank_listen_sk(struct request_sock
 	return lopt;
 }
 
-static inline void __reqsk_queue_destroy(struct request_sock_queue *queue)
-{
-	kfree(reqsk_queue_yank_listen_sk(queue));
-}
-
+extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 
 static inline struct request_sock *
diff --git a/net/core/request_sock.c b/net/core/request_sock.c
index 5f0818d..12a15f5 100644
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ -71,6 +71,20 @@ int reqsk_queue_alloc(struct request_sock_queue *queue,
 
 EXPORT_SYMBOL(reqsk_queue_alloc);
 
+void __reqsk_queue_destroy(struct request_sock_queue *queue)
+{
+	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);
+	size_t lopt_size = sizeof(struct listen_sock) +
+		lopt->nr_table_entries * sizeof(struct request_sock *);
+
+	if (lopt_size > PAGE_SIZE)
+		vfree(lopt);
+	else
+		kfree(lopt);
+}
+
+EXPORT_SYMBOL(__reqsk_queue_destroy);
+
 void reqsk_queue_destroy(struct request_sock_queue *queue)
 {
 	/* make all the listen_opt local to us */

Re: [PATCH 1/2][INET] Fix potential kfree on vmalloc-ed area of request_sock_queue

[Eric Dumazet]

On Wed, 14 Nov 2007 21:08:29 +0300
Pavel Emelyanov <xemul@openvz.org> wrote:

> The request_sock_queue's listen_opt is either vmalloc-ed or
> kmalloc-ed depending on the number of table entries. Thus it 
> is expected to be handled properly on free, which is done in 
> the reqsk_queue_destroy().
> 
> However the error path in inet_csk_listen_start() calls 
> the lite version of reqsk_queue_destroy, called 
> __reqsk_queue_destroy, which calls the kfree unconditionally. 
> 
> Fix this and move the __reqsk_queue_destroy into a .c file as 
> it looks too big to be inline.
> 
> Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
> 
> ---
> 

> +void __reqsk_queue_destroy(struct request_sock_queue *queue)
> +{
> +	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);

WARNING : lopt can be NULL here (or else the locking in reqsk_queue_yank_listen_sk() would be useless ?)

kfree(NULL) was ok, not NULL->nr_table_entries :)

> +	size_t lopt_size = sizeof(struct listen_sock) +
> +		lopt->nr_table_entries * sizeof(struct request_sock *);
> +
> +	if (lopt_size > PAGE_SIZE)
> +		vfree(lopt);
> +	else
> +		kfree(lopt);
> +}

Re: [PATCH 1/2][INET] Fix potential kfree on vmalloc-ed area of request_sock_queue

[David Miller]

From: Eric Dumazet <dada1@cosmosbay.com>
Date: Wed, 14 Nov 2007 20:42:38 +0100

> On Wed, 14 Nov 2007 21:08:29 +0300
> Pavel Emelyanov <xemul@openvz.org> wrote:
> 
> > The request_sock_queue's listen_opt is either vmalloc-ed or
> > kmalloc-ed depending on the number of table entries. Thus it 
> > is expected to be handled properly on free, which is done in 
> > the reqsk_queue_destroy().
> > 
> > However the error path in inet_csk_listen_start() calls 
> > the lite version of reqsk_queue_destroy, called 
> > __reqsk_queue_destroy, which calls the kfree unconditionally. 
> > 
> > Fix this and move the __reqsk_queue_destroy into a .c file as 
> > it looks too big to be inline.
> > 
> > Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
> > 
> > ---
> > 
> 
> > +void __reqsk_queue_destroy(struct request_sock_queue *queue)
> > +{
> > +	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);
> 
> WARNING : lopt can be NULL here (or else the locking in reqsk_queue_yank_listen_sk() would be useless ?)
> 
> kfree(NULL) was ok, not NULL->nr_table_entries :)

I think for the error recovery case he is trying to fix all of this
locking is unnecessary and we know lopt is not NULL.

Pavel can you rework your fix a bit to deal with this?

Thanks a lot.