From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226S8TS4vRoePzFT7UuR7by4esb/NStL8maQUf+h/6k460zrYd0ZLldEIuTIUu5J5ZRkJw4U ARC-Seal: i=1; a=rsa-sha256; t=1517256601; cv=none; d=google.com; s=arc-20160816; b=tuYUoCqbQ6I1hOv4S6ZXHUbrVTWZBOOy7lhF/GHVbKBWlgK9417RW/hZkoqyUe3ij1 qg7F2mzyW8iyxLU+DsFr35Ou1fco6yt3zMjvpgzCSSZB8IcWAjr9ZbNqZs0Vr7UT1srv mKUrRrucsgTnP8fdGmtZLg6cEbhyLVWqGmfiqt6dmWbNZlZfIxRg3SfvkGXMXmeGvDst bLeoleX3wPZCYw1ucNgNGkeTTKldFhxAU7k7Gx1KjQsEfAessWTbw/eQ2quY1O5f2BSA CYI+H9M+GSDWR76jm5gyJp2gvQeeOzXf9NX7ElwQB4MZYmrUA+iIztLnK/rTorx3nG9K rCsA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=NVVPFvvkEXqlwwrwjYNqjmX2JG5h94cEr62KBeY9qmo=; b=QNvkqkn0H8eg0vnpDZjWkktIy9/xSC45bX9pnSmE/dNqpXSvQYOMsLDRAft8lFhsO/ LnhyWHLx78+gAsP4twltRkZmxFwVaYW5Fe8V2m5uSe/F1JZxa3mtePgg7MhY+m/efd+R d+6w5sGx4Zrdm448BGcET3UslVb1u2S3V+IdxQbHRi+psrQbESi13J1Mc/i6fCDkZKPy 2MhmaXw9oD7EFdwST0QKA2vI2yHTIRAwYpGIW7QGaDhnvv8+VhbeEmfGbPyD/8y03N4W PCL2lhZ82+KOPspuRbNvhwLaI+98oJq35iKhAUrL8JteEhOmWqiBHMU905Fq2nS6Ku2z B/DQ== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+ac6ea7baa4432811eb50@syzkaller.appspotmail.com, Xin Long , Neil Horman , "David S. Miller" Subject: [PATCH 3.18 48/52] sctp: return error if the asoc has been peeled off in sctp_wait_for_sndbuf Date: Mon, 29 Jan 2018 13:57:06 +0100 Message-Id: <20180129123630.270180446@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180129123628.168904217@linuxfoundation.org> References: <20180129123628.168904217@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1590958497909596692?= X-GMAIL-MSGID: =?utf-8?q?1590958858784083817?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long [ Upstream commit a0ff660058b88d12625a783ce9e5c1371c87951f ] After commit cea0cc80a677 ("sctp: use the right sk after waking up from wait_buf sleep"), it may change to lock another sk if the asoc has been peeled off in sctp_wait_for_sndbuf. However, the asoc's new sk could be already closed elsewhere, as it's in the sendmsg context of the old sk that can't avoid the new sk's closing. If the sk's last one refcnt is held by this asoc, later on after putting this asoc, the new sk will be freed, while under it's own lock. This patch is to revert that commit, but fix the old issue by returning error under the old sk's lock. Fixes: cea0cc80a677 ("sctp: use the right sk after waking up from wait_buf sleep") Reported-by: syzbot+ac6ea7baa4432811eb50@syzkaller.appspotmail.com Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/socket.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -83,7 +83,7 @@ static int sctp_writeable(struct sock *sk); static void sctp_wfree(struct sk_buff *skb); static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p, - size_t msg_len, struct sock **orig_sk); + size_t msg_len); static int sctp_wait_for_packet(struct sock *sk, int *err, long *timeo_p); static int sctp_wait_for_connect(struct sctp_association *, long *timeo_p); static int sctp_wait_for_accept(struct sock *sk, long timeo); @@ -1948,7 +1948,7 @@ static int sctp_sendmsg(struct kiocb *io timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); if (!sctp_wspace(asoc)) { /* sk can be changed by peel off when waiting for buf. */ - err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len, &sk); + err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len); if (err) { if (err == -ESRCH) { /* asoc is already dead. */ @@ -6981,12 +6981,12 @@ void sctp_sock_rfree(struct sk_buff *skb /* Helper function to wait for space in the sndbuf. */ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p, - size_t msg_len, struct sock **orig_sk) + size_t msg_len) { struct sock *sk = asoc->base.sk; - int err = 0; long current_timeo = *timeo_p; DEFINE_WAIT(wait); + int err = 0; pr_debug("%s: asoc:%p, timeo:%ld, msg_len:%zu\n", __func__, asoc, *timeo_p, msg_len); @@ -7015,17 +7015,13 @@ static int sctp_wait_for_sndbuf(struct s release_sock(sk); current_timeo = schedule_timeout(current_timeo); lock_sock(sk); - if (sk != asoc->base.sk) { - release_sock(sk); - sk = asoc->base.sk; - lock_sock(sk); - } + if (sk != asoc->base.sk) + goto do_error; *timeo_p = current_timeo; } out: - *orig_sk = sk; finish_wait(&asoc->wait, &wait); /* Release the association's refcnt. */