* [PATCH] net: xfrm: fix memory leak in xfrm_user_rcv_msg
@ 2021-06-25 10:23 Pavel Skripkin
2021-06-30 6:51 ` Steffen Klassert
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Skripkin @ 2021-06-25 10:23 UTC (permalink / raw)
To: steffen.klassert, herbert, davem, 0x7f454c46
Cc: netdev, linux-kernel, linux-kernel-mentees, Pavel Skripkin,
syzbot+fb347cf82c73a90efcca
Syzbot reported memory leak in xfrm_user_rcv_msg(). The
problem was is non-freed skb's frag_list.
In skb_release_all() skb_release_data() will be called only
in case of skb->head != NULL, but netlink_skb_destructor()
sets head to NULL. So, allocated frag_list skb should be
freed manualy, since consume_skb() won't take care of it
Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator")
Reported-and-tested-by: syzbot+fb347cf82c73a90efcca@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
One thing I'm not sure about is did I choose the rigth
place to free this skb, maybe we can move this clean up
a little bit deeper, like in xfrm_alloc_userspi()?
---
net/xfrm/xfrm_user.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index f0aecee4d539..ff60ff804074 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2811,6 +2811,16 @@ static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
err = link->doit(skb, nlh, attrs);
+ /* We need to free skb allocated in xfrm_alloc_compat() before
+ * returning from this function, because consume_skb() won't take
+ * care of frag_list since netlink destructor sets
+ * sbk->head to NULL. (see netlink_skb_destructor())
+ */
+ if (skb_has_frag_list(skb)) {
+ kfree_skb(skb_shinfo(skb)->frag_list);
+ skb_shinfo(skb)->frag_list = NULL;
+ }
+
err:
kvfree(nlh64);
return err;
--
2.32.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] net: xfrm: fix memory leak in xfrm_user_rcv_msg
2021-06-25 10:23 [PATCH] net: xfrm: fix memory leak in xfrm_user_rcv_msg Pavel Skripkin
@ 2021-06-30 6:51 ` Steffen Klassert
0 siblings, 0 replies; 2+ messages in thread
From: Steffen Klassert @ 2021-06-30 6:51 UTC (permalink / raw)
To: Pavel Skripkin
Cc: herbert, davem, 0x7f454c46, netdev, linux-kernel,
linux-kernel-mentees, syzbot+fb347cf82c73a90efcca
On Fri, Jun 25, 2021 at 01:23:54PM +0300, Pavel Skripkin wrote:
> Syzbot reported memory leak in xfrm_user_rcv_msg(). The
> problem was is non-freed skb's frag_list.
>
> In skb_release_all() skb_release_data() will be called only
> in case of skb->head != NULL, but netlink_skb_destructor()
> sets head to NULL. So, allocated frag_list skb should be
> freed manualy, since consume_skb() won't take care of it
>
> Fixes: 5106f4a8acff ("xfrm/compat: Add 32=>64-bit messages translator")
> Reported-and-tested-by: syzbot+fb347cf82c73a90efcca@syzkaller.appspotmail.com
> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Applied, thanks a lot!
^ permalink raw reply [flat|nested] 2+ messages in thread
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