[PATCH net-next V4] ptp: fix corrupted list in ptp_open

[PATCH net-next V4] ptp: fix corrupted list in ptp_open

[Edward Adam Davis]

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: syzbot+df3f3ef31f60781fa911@syzkaller.appspotmail.com
Fixes: 8f5de6fb2453 ("ptp: support multiple timestamp event readers")
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
---
 drivers/ptp/ptp_chardev.c | 13 +++++++++----
 drivers/ptp/ptp_clock.c   |  3 +++
 drivers/ptp/ptp_private.h |  1 +
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 282cd7d24077..ba035d6c81ae 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 +143,16 @@ 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) {
+		mutex_lock(&ptp->tsevq_mux);
 		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 +592,5 @@ 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..7d82960fd946 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 writing the timestamp fifo list */
 	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

Re: [PATCH net-next V4] ptp: fix corrupted list in ptp_open

[kernel test robot]

Hi Edward,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]

url:    https://github.com/intel-lab-lkp/linux/commits/Edward-Adam-Davis/ptp-fix-corrupted-list-in-ptp_open/20231104-112916
base:   net-next/main
patch link:    https://lore.kernel.org/r/tencent_8A38BBB333189E6E1B4A4B821BF82569BA08%40qq.com
patch subject: [PATCH net-next V4] ptp: fix corrupted list in ptp_open
config: arc-randconfig-001-20231104 (https://download.01.org/0day-ci/archive/20231104/202311041344.zDyYh5Ty-lkp@intel.com/config)
compiler: arc-elf-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231104/202311041344.zDyYh5Ty-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202311041344.zDyYh5Ty-lkp@intel.com/

All warnings (new ones prefixed by >>):

   drivers/ptp/ptp_chardev.c: In function 'ptp_release':
>> drivers/ptp/ptp_chardev.c:148:23: warning: unused variable 'flags' [-Wunused-variable]
     148 |         unsigned long flags;
         |                       ^~~~~


vim +/flags +148 drivers/ptp/ptp_chardev.c

8f5de6fb245326 Xabier Marquiegui 2023-10-12  142  
8f5de6fb245326 Xabier Marquiegui 2023-10-12  143  int ptp_release(struct posix_clock_context *pccontext)
8f5de6fb245326 Xabier Marquiegui 2023-10-12  144  {
8f5de6fb245326 Xabier Marquiegui 2023-10-12  145  	struct timestamp_event_queue *queue = pccontext->private_clkdata;
f0e5eaa3097d80 Edward Adam Davis 2023-11-04  146  	struct ptp_clock *ptp =
f0e5eaa3097d80 Edward Adam Davis 2023-11-04  147  		container_of(pccontext->clk, struct ptp_clock, clock);
8f5de6fb245326 Xabier Marquiegui 2023-10-12 @148  	unsigned long flags;
8f5de6fb245326 Xabier Marquiegui 2023-10-12  149  
8f5de6fb245326 Xabier Marquiegui 2023-10-12  150  	if (queue) {
f0e5eaa3097d80 Edward Adam Davis 2023-11-04  151  		mutex_lock(&ptp->tsevq_mux);
403376ddb4221b Xabier Marquiegui 2023-10-12  152  		debugfs_remove(queue->debugfs_instance);
8f5de6fb245326 Xabier Marquiegui 2023-10-12  153  		pccontext->private_clkdata = NULL;
8f5de6fb245326 Xabier Marquiegui 2023-10-12  154  		list_del(&queue->qlist);
f0e5eaa3097d80 Edward Adam Davis 2023-11-04  155  		mutex_unlock(&ptp->tsevq_mux);
c5a445b1e9347b Xabier Marquiegui 2023-10-12  156  		bitmap_free(queue->mask);
8f5de6fb245326 Xabier Marquiegui 2023-10-12  157  		kfree(queue);
8f5de6fb245326 Xabier Marquiegui 2023-10-12  158  	}
d94ba80ebbea17 Richard Cochran   2011-04-22  159  	return 0;
d94ba80ebbea17 Richard Cochran   2011-04-22  160  }
d94ba80ebbea17 Richard Cochran   2011-04-22  161  

-- 
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https://github.com/intel/lkp-tests/wiki