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    Subject[PATCH 5.10 004/135] net: xfrm: fix memory leak in xfrm_user_rcv_msg
    Date
    From: Pavel Skripkin <paskripkin@gmail.com>

    [ Upstream commit 7c1a80e80cde008f271bae630d28cf684351e807 ]

    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>
    Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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 45f86a97eaf2..6f97665b632e 100644
    --- a/net/xfrm/xfrm_user.c
    +++ b/net/xfrm/xfrm_user.c
    @@ -2751,6 +2751,16 @@ 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;
    --
    2.30.2


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