Re: [syzbot] [PATCH] Test for 2030579113a1

From: syzbot
Date: Fri Nov 03 2023 - 07:29:26 EST


For archival purposes, forwarding an incoming command email to
linux-kernel@xxxxxxxxxxxxxxx.

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@xxxxxx

please test BUG: corrupted list in ptp_open

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 2dac75696c6d

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 282cd7d24077..6e9762a54b14 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -119,8 +119,13 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
}
bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
spin_lock_init(&queue->lock);
+ if (mutex_lock_interruptible(&ptp->tsevq_mux)) {
+ kfree(queue);
+ return -ERESTARTSYS;
+ }
list_add_tail(&queue->qlist, &ptp->tsevqs);
pccontext->private_clkdata = queue;
+ mutex_unlock(&ptp->tsevq_mux);

/* Debugfs contents */
sprintf(debugfsname, "0x%p", queue);
@@ -138,14 +143,19 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
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);
list_del(&queue->qlist);
spin_unlock_irqrestore(&queue->lock, flags);
+ mutex_unlock(&ptp->tsevq_mux);
bitmap_free(queue->mask);
kfree(queue);
}
@@ -585,7 +595,5 @@ 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