From ed99822817cb728eee8786c1c921c69c6be206fe Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Thu, 20 Jun 2024 13:56:14 -0700 Subject: [PATCH] af_unix: Define locking order for U_LOCK_SECOND in unix_state_double_lock(). unix_dgram_connect() and unix_dgram_{send,recv}msg() lock the socket and peer in ascending order of the socket address. Let's define the order as unix_state_lock_cmp_fn() instead of using unix_state_lock_nested(). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Kent Overstreet Signed-off-by: Paolo Abeni --- net/unix/af_unix.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index 7889d4723959..0657f599bbef 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -134,6 +134,18 @@ static int unix_table_lock_cmp_fn(const struct lockdep_map *a, { return cmp_ptr(a, b); } + +static int unix_state_lock_cmp_fn(const struct lockdep_map *_a, + const struct lockdep_map *_b) +{ + const struct unix_sock *a, *b; + + a = container_of(_a, struct unix_sock, lock.dep_map); + b = container_of(_b, struct unix_sock, lock.dep_map); + + /* unix_state_double_lock(): ascending address order. */ + return cmp_ptr(a, b); +} #endif static unsigned int unix_unbound_hash(struct sock *sk) @@ -987,6 +999,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, u->path.dentry = NULL; u->path.mnt = NULL; spin_lock_init(&u->lock); + lock_set_cmp_fn(&u->lock, unix_state_lock_cmp_fn, NULL); mutex_init(&u->iolock); /* single task reading lock */ mutex_init(&u->bindlock); /* single task binding lock */ init_waitqueue_head(&u->peer_wait); @@ -1335,11 +1348,12 @@ static void unix_state_double_lock(struct sock *sk1, struct sock *sk2) unix_state_lock(sk1); return; } + if (sk1 > sk2) swap(sk1, sk2); unix_state_lock(sk1); - unix_state_lock_nested(sk2, U_LOCK_SECOND); + unix_state_lock(sk2); } static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)