[CRIU] [PATCH] fix segmentation fault caused by uninitialized mutex

[Andrei Vagin]

Cyrill, could you review this patch?

On Wed, Jun 19, 2019 at 09:13:39AM +0000, Dengguangxing wrote:
> 
> Segmentation fault was raised while trying to restore a process with
> tty. Coredump file says this is caused by uninitialized tty_mutex:
>         (gdb) where
>         #0  0x00000000004d7270 in atomic_add_return (i=1, v=0x0) at
>         include/common/asm/atomic.h:34
>         #1  0x00000000004d7398 in mutex_lock (m=0x0) at
>         include/common/lock.h:151
>         #2  0x00000000004d840c in __pty_open_ptmx_index (index=3, flags=2,
>         cb=0x4dce50 <open_pty>, arg=0x11, path=0x5562e0 "ptmx") at
>         criu/tty.c:603
>         #3  0x00000000004dced8 in pty_create_ptmx_index (dfd=17, index=3,
>         flags=2) at criu/tty.c:2384
> 
> since init_tty_mutex() is reentrantable, just calling it before
> mutex_lock()
> 
> Signed-off-by: Deng Guangxing <dengguangxing at huawei.com>
> ---
>  criu/tty.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/criu/tty.c b/criu/tty.c
> index 6fe11530..e9a28897 100644
> --- a/criu/tty.c
> +++ b/criu/tty.c
> @@ -600,6 +600,9 @@ static int __pty_open_ptmx_index(int index, int flags,
> 
>         memset(fds, 0xff, sizeof(fds));
> 
> +       if (init_tty_mutex())
> +               return -1;
> +
>         mutex_lock(tty_mutex);
> 
>         for (i = 0; i < ARRAY_SIZE(fds); i++) {
> --
> 2.17.1
> 
> 
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