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Commit da407a00 authored by Paulo Alcantara's avatar Paulo Alcantara Committed by Greg Kroah-Hartman
Browse files

cifs: fix potential use-after-free in cifs_echo_request() 



commit 212253367dc7b49ed3fc194ce71b0992eacaecf2 upstream.

This patch fixes a potential use-after-free bug in
cifs_echo_request().

For instance,

  thread 1
  --------
  cifs_demultiplex_thread()
    clean_demultiplex_info()
      kfree(server)

  thread 2 (workqueue)
  --------
  apic_timer_interrupt()
    smp_apic_timer_interrupt()
      irq_exit()
        __do_softirq()
          run_timer_softirq()
            call_timer_fn()
	      cifs_echo_request() <- use-after-free in server ptr

Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
CC: Stable <stable@vger.kernel.org>
Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3920afb5

fs/cifs/connect.c

+2 −0
Original line number Diff line number Diff line
@@ -730,6 +730,8 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server) 
	list_del_init(&server->tcp_ses_list);

	spin_unlock(&cifs_tcp_ses_lock);



	cancel_delayed_work_sync(&server->echo);



	spin_lock(&GlobalMid_Lock);

	server->tcpStatus = CifsExiting;

	spin_unlock(&GlobalMid_Lock);