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SubjectRe: [PATCH 4/4] tty: n_gsm: fix missing corner cases in gsmld_poll()
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On 06. 07. 22, 7:44, D. Starke wrote:
> From: Daniel Starke <daniel.starke@siemens.com>
>
> gsmld_poll() currently fails to handle some corner cases correctly:
> - tty ldisc association lost
> - remote party closed the associated tty
>
> Add the missing checks and map those to EPOLLHUP.
> Reorder the checks to group them by their reaction.
>
> Fixes: e1eaea46bb40 ("tty: n_gsm line discipline")
> Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
> ---
> drivers/tty/n_gsm.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> Based on tty-testing.
>
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index 51447ccccbab..47566bd2ed6e 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -3051,14 +3051,20 @@ static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
> __poll_t mask = 0;
> struct gsm_mux *gsm = tty->disc_data;
>
> + if (!gsm)
> + return EPOLLHUP;

Hmm, how can this happen? It's a tty bug if it calls ld ops after
NULLing disc_data.

thanks,
--
js
suse labs

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