[PATCH net-next V2] ptp: fix corrupted list in ptp_open

[PATCH net-next V2] 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 | 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

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Richard Cochran]

On Tue, Oct 31, 2023 at 06:25:42PM +0800, Edward Adam Davis wrote:
> There is no lock protection when writing ptp->tsevqs in ptp_open(),
> ptp_release(), which can cause data corruption,

NAK.

You haven't identified any actual data corruption issue.

If there is an issue, please state what it is.

Thanks,
Richard

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Jeremy Cline]

Hi Edward,

On Tue, Oct 31, 2023 at 06:25:42PM +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: 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 | 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);

The lock doesn't need to be held so long here. Doing so causes a bit of
an issue, actually, because the memory allocation for the queue can fail
which will cause the function to return early without releasing the
mutex.

The lock only needs to be held for the list_add_tail() call.

>  	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);

Similar to the above note, you don't want to hold the lock any longer
than you must.

While this patch looks to cover adding and removing items from the list,
the code that iterates over the list isn't covered which can be
problematic. If the list is modified while it is being iterated, the
iterating code could chase an invalid pointer.

Regards,
Jeremy

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Edward Adam Davis]

Hi Jeremy,

On Thu, 2 Nov 2023 14:16:54 -0400 Jeremy Cline 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: 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 | 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);
>
>The lock doesn't need to be held so long here. Doing so causes a bit of
>an issue, actually, because the memory allocation for the queue can fail
>which will cause the function to return early without releasing the
>mutex.
>
>The lock only needs to be held for the list_add_tail() call.
>
>>  	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);
>
>Similar to the above note, you don't want to hold the lock any longer
>than you must.
>
>While this patch looks to cover adding and removing items from the list,
>the code that iterates over the list isn't covered which can be
>problematic. If the list is modified while it is being iterated, the
>iterating code could chase an invalid pointer.
Thanks for your opinions, I will double check it.

Thanks,
edward

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Richard Cochran]

On Thu, Nov 02, 2023 at 02:16:54PM -0400, Jeremy Cline wrote:

> While this patch looks to cover adding and removing items from the list,
> the code that iterates over the list isn't covered which can be
> problematic. If the list is modified while it is being iterated, the
> iterating code could chase an invalid pointer.

Indeed.

See ptp_clock.c:

 416         case PTP_CLOCK_EXTTS:
 417                 /* Enqueue timestamp on selected queues */
 418                 list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
 419                         if (test_bit((unsigned int)event->index, tsevq->mask))
 420                                 enqueue_external_timestamp(tsevq, event);
 421                 }
 422                 wake_up_interruptible(&ptp->tsev_wq);
 423                 break;

Thanks,
Richard

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Richard Cochran]

On Fri, Nov 03, 2023 at 07:13:31PM -0700, Richard Cochran wrote:
> See ptp_clock.c:
> 
>  416         case PTP_CLOCK_EXTTS:
>  417                 /* Enqueue timestamp on selected queues */
>  418                 list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
>  419                         if (test_bit((unsigned int)event->index, tsevq->mask))
>  420                                 enqueue_external_timestamp(tsevq, event);
>  421                 }
>  422                 wake_up_interruptible(&ptp->tsev_wq);
>  423                 break;

And that code can be called from interrupt context.

Thus the mutex won't work.

It needs to be a spin lock instead.

Thanks,
Richard

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Richard Cochran]

On Thu, Nov 02, 2023 at 07:16:17PM +0800, Edward Adam Davis wrote:
> The above two logs can clearly indicate that there is corruption when 
> executing the operation of writing ptp->tsevqs in ptp_open() and ptp_release().

So just remove the bogus call to ptp_release.

Thanks,
Richard

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Edward Adam Davis]

On Wed, 1 Nov 2023 17:12:53 -0700 Richard Cochran wrote:
>> There is no lock protection when writing ptp->tsevqs in ptp_open(),
>> ptp_release(), which can cause data corruption,
>
>Really?  How?
Let me show the corruption that occurs in ptp_open() and ptp_release(), 

1. Corruption that appears in ptp_open(),
Link: https://syzkaller.appspot.com/bug?extid=df3f3ef31f60781fa911

list_add corruption. prev->next should be next (ffff88814a1325e8), but was ffff888078d25048. (prev=ffff888078d21048).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:32!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 7237 Comm: syz-executor182 Not tainted 6.6.0-rc6-next-20231020-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
RIP: 0010:__list_add_valid_or_report+0xb6/0x100 lib/list_debug.c:32
Code: e8 2f a5 3a fd 0f 0b 48 89 d9 48 c7 c7 40 9d e9 8a e8 1e a5 3a fd 0f 0b 48 89 f1 48 c7 c7 c0 9d e9 8a 48 89 de e8 0a a5 3a fd <0f> 0b 48 89 f2 48 89 d9 48 89 ee 48 c7 c7 40 9e e9 8a e8 f3 a4 3a
RSP: 0018:ffffc90009b3f898 EFLAGS: 00010286
RAX: 0000000000000075 RBX: ffff88814a1325e8 RCX: ffffffff816bb8d9
RDX: 0000000000000000 RSI: ffffffff816c4d42 RDI: 0000000000000005
RBP: ffff88807c7a9048 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000001 R12: ffff88814a132000
R13: ffffc90009b3f900 R14: ffff888078d21048 R15: ffff88807c7a9048
FS:  0000555556c00380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffef0aa1138 CR3: 000000007d17e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __list_add_valid include/linux/list.h:88 [inline]
 __list_add include/linux/list.h:150 [inline]
 list_add_tail include/linux/list.h:183 [inline]
 ptp_open+0x1c5/0x4f0 drivers/ptp/ptp_chardev.c:122
 posix_clock_open+0x17e/0x240 kernel/time/posix-clock.c:134
 chrdev_open+0x26d/0x6e0 fs/char_dev.c:414
 do_dentry_open+0x8d4/0x18d0 fs/open.c:948
 do_open fs/namei.c:3621 [inline]
 path_openat+0x1d36/0x2cd0 fs/namei.c:3778
 do_filp_open+0x1dc/0x430 fs/namei.c:3808
 do_sys_openat2+0x176/0x1e0 fs/open.c:1440
 do_sys_open fs/open.c:1455 [inline]
 __do_sys_openat fs/open.c:1471 [inline]
 __se_sys_openat fs/open.c:1466 [inline]
 __x64_sys_openat+0x175/0x210 fs/open.c:1466
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fc6c2099ae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffef0aa1238 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc6c2099ae9
RDX: 0000000000000000 RSI: 0000000020000300 RDI: ffffffffffffff9c
RBP: 00000000000f4240 R08: 0000000000000000 R09: 00000000000000a0
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000000130fc
R13: 00007ffef0aa124c R14: 00007ffef0aa1260 R15: 00007ffef0aa1250
 </TASK>

2. Corruption that appears in ptp_open(),
Link: https://syzkaller.appspot.com/x/log.txt?x=169a58d1680000

list_del corruption. prev->next should be ffff8880280e5048, but was ffff888025dc1048. (prev=ffff88814adb1048)
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:62!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 13142 Comm: syz-executor.2 Not tainted 6.6.0-rc6-next-20231018-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
RIP: 0010:__list_del_entry_valid_or_report+0x11f/0x1b0
Code: 8f e9 8a e8 c3 d3 3a fd 0f 0b 48 89 ca 48 c7 c7 e0 8f e9 8a e8 b2 d3 3a fd 0f 0b 48 89 c2 48 c7 c7 40 90 e9 8a e8 a1 d3 3a fd <0f> 0b 48 89 d1 48 c7 c7 c0 90 e9 8a 48 89 c2 e8 8d d3 3a fd 0f 0b
RSP: 0018:ffffc90003167e08 EFLAGS: 00010086
RAX: 000000000000006d RBX: ffff8880280e4000 RCX: ffffffff816b9cd9
RDX: 0000000000000000 RSI: ffffffff816c3142 RDI: 0000000000000005
RBP: ffff888023b7c480 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000001 R11: 0000000000000001 R12: 0000000000000293
R13: ffff8880280e5008 R14: ffff8880280e5048 R15: ffff8880280e5050
FS:  00005555557e3480(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f350fd98000 CR3: 000000002427a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ptp_release+0xca/0x2a0
 posix_clock_release+0xa4/0x160
 __fput+0x270/0xbb0
 __fput_sync+0x47/0x50
 __x64_sys_close+0x87/0xf0
 do_syscall_64+0x3f/0x110
 entry_SYSCALL_64_after_hwframe+0x63/0x6b 


The above two logs can clearly indicate that there is corruption when 
executing the operation of writing ptp->tsevqs in ptp_open() and ptp_release().
>
>> 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 | 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;
>> +
>
>This mutex is not needed.
>
>Please don't ignore review comments.

Thanks,
edward

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Richard Cochran]

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,

Really?  How?

> 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 | 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;
> +

This mutex is not needed.

Please don't ignore review comments.

Thanks,
Richard

Re: [PATCH net-next V2] ptp: fix corrupted list in ptp_open

[Martin Habets]

Please use a separate mail thread for a new patch revision.
See the section "Resending after review" in
Documentation/process/maintainer-netdev.rst.

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: 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 | 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
> 

[PATCH net-next V2] 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 | 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