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Martin
On Tue, Oct 31, 2023 at 05:07:08AM +0800, Edward Adam Davis wrote:
> There is no lock protection when writing ptp->tsevqs in ptp_open(),
> ptp_release(), which can cause data corruption, use mutex lock to avoid this
> issue.
>
> Moreover, ptp_release() should not be used to release the queue in ptp_read(),
> and it should be deleted together.
>
> Reported-and-tested-by: [email protected]
> Fixes: 8f5de6fb2453 ("ptp: support multiple timestamp event readers")
> Signed-off-by: Edward Adam Davis <[email protected]>
> ---
> drivers/ptp/ptp_chardev.c | 11 +++++++++--
> drivers/ptp/ptp_clock.c | 3 +++
> drivers/ptp/ptp_private.h | 1 +
> 3 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 282cd7d24077..e31551d2697d 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -109,6 +109,9 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
> struct timestamp_event_queue *queue;
> char debugfsname[32];
>
> + if (mutex_lock_interruptible(&ptp->tsevq_mux))
> + return -ERESTARTSYS;
> +
> queue = kzalloc(sizeof(*queue), GFP_KERNEL);
> if (!queue)
> return -EINVAL;
> @@ -132,15 +135,20 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
> debugfs_create_u32_array("mask", 0444, queue->debugfs_instance,
> &queue->dfs_bitmap);
>
> + mutex_unlock(&ptp->tsevq_mux);
> return 0;
> }
>
> int ptp_release(struct posix_clock_context *pccontext)
> {
> struct timestamp_event_queue *queue = pccontext->private_clkdata;
> + struct ptp_clock *ptp =
> + container_of(pccontext->clk, struct ptp_clock, clock);
> unsigned long flags;
>
> if (queue) {
> + if (mutex_lock_interruptible(&ptp->tsevq_mux))
> + return -ERESTARTSYS;
> debugfs_remove(queue->debugfs_instance);
> pccontext->private_clkdata = NULL;
> spin_lock_irqsave(&queue->lock, flags);
> @@ -148,6 +156,7 @@ int ptp_release(struct posix_clock_context *pccontext)
> spin_unlock_irqrestore(&queue->lock, flags);
> bitmap_free(queue->mask);
> kfree(queue);
> + mutex_unlock(&ptp->tsevq_mux);
> }
> return 0;
> }
> @@ -585,7 +594,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
> free_event:
> kfree(event);
> exit:
> - if (result < 0)
> - ptp_release(pccontext);
> return result;
> }
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index 3d1b0a97301c..7930db6ec18d 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -176,6 +176,7 @@ static void ptp_clock_release(struct device *dev)
>
> ptp_cleanup_pin_groups(ptp);
> kfree(ptp->vclock_index);
> + mutex_destroy(&ptp->tsevq_mux);
> mutex_destroy(&ptp->pincfg_mux);
> mutex_destroy(&ptp->n_vclocks_mux);
> /* Delete first entry */
> @@ -247,6 +248,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> if (!queue)
> goto no_memory_queue;
> list_add_tail(&queue->qlist, &ptp->tsevqs);
> + mutex_init(&ptp->tsevq_mux);
> queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
> if (!queue->mask)
> goto no_memory_bitmap;
> @@ -356,6 +358,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> if (ptp->kworker)
> kthread_destroy_worker(ptp->kworker);
> kworker_err:
> + mutex_destroy(&ptp->tsevq_mux);
> mutex_destroy(&ptp->pincfg_mux);
> mutex_destroy(&ptp->n_vclocks_mux);
> bitmap_free(queue->mask);
> diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> index 52f87e394aa6..1525bd2059ba 100644
> --- a/drivers/ptp/ptp_private.h
> +++ b/drivers/ptp/ptp_private.h
> @@ -44,6 +44,7 @@ struct ptp_clock {
> struct pps_device *pps_source;
> long dialed_frequency; /* remembers the frequency adjustment */
> struct list_head tsevqs; /* timestamp fifo list */
> + struct mutex tsevq_mux; /* one process at a time reading the fifo */
> struct mutex pincfg_mux; /* protect concurrent info->pin_config access */
> wait_queue_head_t tsev_wq;
> int defunct; /* tells readers to go away when clock is being removed */
> --
> 2.25.1
>