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| author | Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru> | 2024-06-13 08:23:00 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2024-06-17 13:06:23 +0100 |
| commit | 0b9130247f3b6a1122478471ff0e014ea96bb735 (patch) | |
| tree | 1577d9f564baf9f758da4aed42740bd5619c4d4c /net | |
| parent | 143492fce36161402fa2f45a0756de7ff69c366a (diff) | |
| download | linux-0b9130247f3b6a1122478471ff0e014ea96bb735.tar.gz linux-0b9130247f3b6a1122478471ff0e014ea96bb735.tar.bz2 linux-0b9130247f3b6a1122478471ff0e014ea96bb735.zip | |
netrom: Fix a memory leak in nr_heartbeat_expiry()
syzbot reported a memory leak in nr_create() [0].
Commit 409db27e3a2e ("netrom: Fix use-after-free of a listening socket.")
added sock_hold() to the nr_heartbeat_expiry() function, where
a) a socket has a SOCK_DESTROY flag or
b) a listening socket has a SOCK_DEAD flag.
But in the case "a," when the SOCK_DESTROY flag is set, the file descriptor
has already been closed and the nr_release() function has been called.
So it makes no sense to hold the reference count because no one will
call another nr_destroy_socket() and put it as in the case "b."
nr_connect
nr_establish_data_link
nr_start_heartbeat
nr_release
switch (nr->state)
case NR_STATE_3
nr->state = NR_STATE_2
sock_set_flag(sk, SOCK_DESTROY);
nr_rx_frame
nr_process_rx_frame
switch (nr->state)
case NR_STATE_2
nr_state2_machine()
nr_disconnect()
nr_sk(sk)->state = NR_STATE_0
sock_set_flag(sk, SOCK_DEAD)
nr_heartbeat_expiry
switch (nr->state)
case NR_STATE_0
if (sock_flag(sk, SOCK_DESTROY) ||
(sk->sk_state == TCP_LISTEN
&& sock_flag(sk, SOCK_DEAD)))
sock_hold() // ( !!! )
nr_destroy_socket()
To fix the memory leak, let's call sock_hold() only for a listening socket.
Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with Syzkaller.
[0]: https://syzkaller.appspot.com/bug?extid=d327a1f3b12e1e206c16
Reported-by: syzbot+d327a1f3b12e1e206c16@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d327a1f3b12e1e206c16
Fixes: 409db27e3a2e ("netrom: Fix use-after-free of a listening socket.")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netrom/nr_timer.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/netrom/nr_timer.c b/net/netrom/nr_timer.c index 4e7c968cde2d..5e3ca068f04e 100644 --- a/net/netrom/nr_timer.c +++ b/net/netrom/nr_timer.c @@ -121,7 +121,8 @@ static void nr_heartbeat_expiry(struct timer_list *t) is accepted() it isn't 'dead' so doesn't get removed. */ if (sock_flag(sk, SOCK_DESTROY) || (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) { - sock_hold(sk); + if (sk->sk_state == TCP_LISTEN) + sock_hold(sk); bh_unlock_sock(sk); nr_destroy_socket(sk); goto out; |