diff mbox series

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

Message ID 20201128195402.12233-1-pc@cjr.nz (mailing list archive)
State New, archived
Headers show
Series cifs: fix potential use-after-free in cifs_echo_request() | expand

Commit Message

Paulo Alcantara Nov. 28, 2020, 7:54 p.m. UTC 
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: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/connect.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Steve French Nov. 30, 2020, 2:31 a.m. UTC | #1 
added Ronnie's reviewed-by to the two patches and put in cifs-2.6.git for-next

On Sat, Nov 28, 2020 at 1:54 PM Paulo Alcantara <pc@cjr.nz> wrote:
>
> 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: Paulo Alcantara (SUSE) <pc@cjr.nz>
> ---
>  fs/cifs/connect.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
> index c38156f324dd..28c1459fb0fc 100644
> --- a/fs/cifs/connect.c
> +++ b/fs/cifs/connect.c
> @@ -876,6 +876,8 @@ 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);
> --
> 2.29.2
>
diff mbox series

Patch

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index c38156f324dd..28c1459fb0fc 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -876,6 +876,8 @@  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);