commit 983512f3a8 upstream.
skb_may_tx_timestamp() may acquire sock::sk_callback_lock. The lock must
not be taken in IRQ context, only softirq is okay. A few drivers receive
the timestamp via a dedicated interrupt and complete the TX timestamp
from that handler. This will lead to a deadlock if the lock is already
write-locked on the same CPU.
Taking the lock can be avoided. The socket (pointed by the skb) will
remain valid until the skb is released. The ->sk_socket and ->file
member will be set to NULL once the user closes the socket which may
happen before the timestamp arrives.
If we happen to observe the pointer while the socket is closing but
before the pointer is set to NULL then we may use it because both
pointer (and the file's cred member) are RCU freed.
Drop the lock. Use READ_ONCE() to obtain the individual pointer. Add a
matching WRITE_ONCE() where the pointer are cleared.
Link: https://lore.kernel.org/all/20260205145104.iWinkXHv@linutronix.de
Fixes: b245be1f4d ("net-timestamp: no-payload only sysctl")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260220183858.N4ERjFW6@linutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[ adapted sk_set_socket() in include/net/sock.h to fix the conflict from
not having commit 5d6b58c932 ("net: lockless sock_i_ino()") and the
additional previous changes required by it.
It comes down to just now having the lines of
if (sock) {
WRITE_ONCE(sk->sk_uid, SOCK_INODE(sock)->i_uid);
WRITE_ONCE(sk->sk_ino, SOCK_INODE(sock)->i_ino);
}
below the changed line. ]
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
3709d73ace