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authorCong Wang <xiyou.wangcong@gmail.com>2018-04-18 11:51:56 -0700
committerDavid S. Miller <davem@davemloft.net>2018-04-19 13:54:53 -0400
commitf7e43672683b097bb074a8fe7af9bc600a23f231 (patch)
treef0177814d3113c0e7672a9d725d7a676d08e397b /net/llc
parentMAINTAINERS: Direct networking documentation changes to netdev (diff)
downloadlinux-dev-f7e43672683b097bb074a8fe7af9bc600a23f231.tar.xz
linux-dev-f7e43672683b097bb074a8fe7af9bc600a23f231.zip
llc: hold llc_sap before release_sock()
syzbot reported we still access llc->sap in llc_backlog_rcv() after it is freed in llc_sap_remove_socket(): Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 llc_conn_ac_send_sabme_cmd_p_set_x+0x3a8/0x460 net/llc/llc_c_ac.c:785 llc_exec_conn_trans_actions net/llc/llc_conn.c:475 [inline] llc_conn_service net/llc/llc_conn.c:400 [inline] llc_conn_state_process+0x4e1/0x13a0 net/llc/llc_conn.c:75 llc_backlog_rcv+0x195/0x1e0 net/llc/llc_conn.c:891 sk_backlog_rcv include/net/sock.h:909 [inline] __release_sock+0x12f/0x3a0 net/core/sock.c:2335 release_sock+0xa4/0x2b0 net/core/sock.c:2850 llc_ui_release+0xc8/0x220 net/llc/af_llc.c:204 llc->sap is refcount'ed and llc_sap_remove_socket() is paired with llc_sap_add_socket(). This can be amended by holding its refcount before llc_sap_remove_socket() and releasing it after release_sock(). Reported-by: <syzbot+6e181fc95081c2cf9051@syzkaller.appspotmail.com> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/llc')
-rw-r--r--net/llc/af_llc.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 01dcc0823d1f..6d29b2b94e84 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -189,6 +189,7 @@ static int llc_ui_release(struct socket *sock)
{
struct sock *sk = sock->sk;
struct llc_sock *llc;
+ struct llc_sap *sap;
if (unlikely(sk == NULL))
goto out;
@@ -199,9 +200,15 @@ static int llc_ui_release(struct socket *sock)
llc->laddr.lsap, llc->daddr.lsap);
if (!llc_send_disc(sk))
llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);
+ sap = llc->sap;
+ /* Hold this for release_sock(), so that llc_backlog_rcv() could still
+ * use it.
+ */
+ llc_sap_hold(sap);
if (!sock_flag(sk, SOCK_ZAPPED))
llc_sap_remove_socket(llc->sap, sk);
release_sock(sk);
+ llc_sap_put(sap);
if (llc->dev)
dev_put(llc->dev);
sock_put(sk);