From: Will Deacon <will@kernel.org>
To: gregkh@linuxfoundation.org
Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@android.com, g.nault@alphalink.fr,
"David S . Miller" <davem@davemloft.net>,
Will Deacon <will@kernel.org>
Subject: [PATCH 4/8] l2tp: ensure session can't get removed during pppol2tp_session_ioctl()
Date: Thu, 2 Apr 2020 18:32:46 +0100 [thread overview]
Message-ID: <20200402173250.7858-5-will@kernel.org> (raw)
In-Reply-To: <20200402173250.7858-1-will@kernel.org>
From: Guillaume Nault <g.nault@alphalink.fr>
commit 57377d63547861919ee634b845c7caa38de4a452 upstream.
Holding a reference on session is required before calling
pppol2tp_session_ioctl(). The session could get freed while processing the
ioctl otherwise. Since pppol2tp_session_ioctl() uses the session's socket,
we also need to take a reference on it in l2tp_session_get().
Fixes: fd558d186df2 ("l2tp: Split pppol2tp patch into separate l2tp and ppp parts")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Will Deacon <will@kernel.org>
---
net/l2tp/l2tp_ppp.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index bc5fca07d2ee..74b211312d4d 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -1168,11 +1168,18 @@ static int pppol2tp_tunnel_ioctl(struct l2tp_tunnel *tunnel,
if (stats.session_id != 0) {
/* resend to session ioctl handler */
struct l2tp_session *session =
- l2tp_session_find(sock_net(sk), tunnel, stats.session_id);
- if (session != NULL)
- err = pppol2tp_session_ioctl(session, cmd, arg);
- else
+ l2tp_session_get(sock_net(sk), tunnel,
+ stats.session_id, true);
+
+ if (session) {
+ err = pppol2tp_session_ioctl(session, cmd,
+ arg);
+ if (session->deref)
+ session->deref(session);
+ l2tp_session_dec_refcount(session);
+ } else {
err = -EBADR;
+ }
break;
}
#ifdef CONFIG_XFRM
--
2.26.0.rc2.310.g2932bb562d-goog
next prev parent reply other threads:[~2020-04-02 17:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-02 17:32 [PATCH 0/8] [backports] l2tp use-after-free fixes for 4.4 stable Will Deacon
2020-04-02 17:32 ` [PATCH 1/8] l2tp: Correctly return -EBADF from pppol2tp_getname Will Deacon
2020-04-02 17:32 ` [PATCH 2/8] net: l2tp: Make l2tp_ip6 namespace aware Will Deacon
2020-04-02 17:32 ` [PATCH 3/8] l2tp: fix race in l2tp_recv_common() Will Deacon
2020-04-02 17:32 ` Will Deacon [this message]
2020-04-02 17:32 ` [PATCH 5/8] l2tp: fix duplicate session creation Will Deacon
2020-04-02 17:32 ` [PATCH 6/8] l2tp: Refactor the codes with existing macros instead of literal number Will Deacon
2020-04-02 17:32 ` [PATCH 7/8] l2tp: ensure sessions are freed after their PPPOL2TP socket Will Deacon
2020-04-02 17:32 ` [PATCH 8/8] l2tp: fix race between l2tp_session_delete() and l2tp_tunnel_closeall() Will Deacon
2020-04-03 12:45 ` [PATCH 0/8] [backports] l2tp use-after-free fixes for 4.4 stable Greg KH
2020-04-03 13:22 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200402173250.7858-5-will@kernel.org \
--to=will@kernel.org \
--cc=davem@davemloft.net \
--cc=g.nault@alphalink.fr \
--cc=gregkh@linuxfoundation.org \
--cc=kernel-team@android.com \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).