[syzbot] [net?] BUG: corrupted list in ptp_open

[syzbot] [net?] BUG: corrupted list in ptp_open

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    2030579113a1 Add linux-next specific files for 20231020
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16ab79a3680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=37404d76b3c8840e
dashboard link: https://syzkaller.appspot.com/bug?extid=df3f3ef31f60781fa911
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=140aa715680000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11037669680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a99a981e5d78/disk-20305791.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/073a5ba6a2a6/vmlinux-20305791.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c7c1a7107f7b/bzImage-20305791.xz

The issue was bisected to:

commit 8f5de6fb245326704f37d91780b9a10253a8a100
Author: Xabier Marquiegui <reibax@gmail.com>
Date:   Wed Oct 11 22:39:55 2023 +0000

    ptp: support multiple timestamp event readers

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=15475b89680000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=17475b89680000
console output: https://syzkaller.appspot.com/x/log.txt?x=13475b89680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+df3f3ef31f60781fa911@syzkaller.appspotmail.com
Fixes: 8f5de6fb2453 ("ptp: support multiple timestamp event readers")

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>
Modules linked in:
---[ end trace 0000000000000000 ]---
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


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

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

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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

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

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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

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

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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..eb4015ae93a2 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 		container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
+	unsigned long flags;
 
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
@@ -119,8 +120,10 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	}
 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
 	spin_lock_init(&queue->lock);
+	spin_lock_irqsave(&ptp->tsevq_lock, flags);
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
 	pccontext->private_clkdata = queue;
+	spin_unlock_irqrestore(&ptp->tsevq_lock, flags);
 
 	/* Debugfs contents */
 	sprintf(debugfsname, "0x%p", queue);
@@ -139,13 +142,15 @@ int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
 	unsigned long flags;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 
 	if (queue) {
 		debugfs_remove(queue->debugfs_instance);
+		spin_lock_irqsave(&ptp->tsevq_lock, flags);
 		pccontext->private_clkdata = NULL;
-		spin_lock_irqsave(&queue->lock, flags);
 		list_del(&queue->qlist);
-		spin_unlock_irqrestore(&queue->lock, flags);
+		spin_unlock_irqrestore(&ptp->tsevq_lock, flags);
 		bitmap_free(queue->mask);
 		kfree(queue);
 	}
@@ -585,7 +590,5 @@ 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..d813bf25dffc 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_lock_init(&ptp->tsevq_lock);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 52f87e394aa6..63af246f17eb 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 */
+	spinlock_t tsevqs_lock; /* 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: [syzbot] [PATCH] Test for 2030579113a1

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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..31594f40a21e 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 		container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
+	unsigned long flags;
 
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
@@ -119,8 +120,10 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	}
 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
 	spin_lock_init(&queue->lock);
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
 	pccontext->private_clkdata = queue;
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 
 	/* Debugfs contents */
 	sprintf(debugfsname, "0x%p", queue);
@@ -139,13 +142,15 @@ int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
 	unsigned long flags;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 
 	if (queue) {
 		debugfs_remove(queue->debugfs_instance);
+		spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 		pccontext->private_clkdata = NULL;
-		spin_lock_irqsave(&queue->lock, flags);
 		list_del(&queue->qlist);
-		spin_unlock_irqrestore(&queue->lock, flags);
+		spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 		bitmap_free(queue->mask);
 		kfree(queue);
 	}
@@ -585,7 +590,5 @@ 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..ea82648ad557 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_lock_init(&ptp->tsevqs_lock);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 52f87e394aa6..63af246f17eb 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 */
+	spinlock_t tsevqs_lock; /* 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: [syzbot] [PATCH] Test for 2030579113a1

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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..3f7a74788802 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 		container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
+	unsigned long flags;
 
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
@@ -119,7 +120,9 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	}
 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
 	spin_lock_init(&queue->lock);
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 	pccontext->private_clkdata = queue;
 
 	/* Debugfs contents */
@@ -139,16 +142,16 @@ int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
 	unsigned long flags;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 
-	if (queue) {
-		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);
-		bitmap_free(queue->mask);
-		kfree(queue);
-	}
+	debugfs_remove(queue->debugfs_instance);
+	pccontext->private_clkdata = NULL;
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
+	list_del(&queue->qlist);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
+	bitmap_free(queue->mask);
+	kfree(queue);
 	return 0;
 }
 
@@ -585,7 +588,5 @@ 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..41b68568811a 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_lock_init(&ptp->tsevqs_lock);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;
@@ -407,6 +408,7 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 {
 	struct timestamp_event_queue *tsevq;
 	struct pps_event_time evt;
+	unsigned long flags;
 
 	switch (event->type) {
 
@@ -415,10 +417,12 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 
 	case PTP_CLOCK_EXTTS:
 		/* Enqueue timestamp on selected queues */
+		spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 		list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
 			if (test_bit((unsigned int)event->index, tsevq->mask))
 				enqueue_external_timestamp(tsevq, event);
 		}
+		spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 		wake_up_interruptible(&ptp->tsev_wq);
 		break;
 
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 52f87e394aa6..35fde0a05746 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 */
+	spinlock_t tsevqs_lock; /* protects tsevqs from concurrent access */
 	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: [syzbot] [PATCH] Test for 2030579113a1

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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..473b6d992507 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 		container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
+	unsigned long flags;
 
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
@@ -119,7 +120,9 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	}
 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
 	spin_lock_init(&queue->lock);
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 	pccontext->private_clkdata = queue;
 
 	/* Debugfs contents */
@@ -139,16 +142,16 @@ int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
 	unsigned long flags;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 
-	if (queue) {
-		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);
-		bitmap_free(queue->mask);
-		kfree(queue);
-	}
+	debugfs_remove(queue->debugfs_instance);
+	pccontext->private_clkdata = NULL;
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
+	list_del(&queue->qlist);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
+	bitmap_free(queue->mask);
+	kfree(queue);
 	return 0;
 }
 
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 3d1b0a97301c..b901f2910963 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -179,11 +179,11 @@ static void ptp_clock_release(struct device *dev)
 	mutex_destroy(&ptp->pincfg_mux);
 	mutex_destroy(&ptp->n_vclocks_mux);
 	/* Delete first entry */
+	spin_lock_irqsave(&tsevq->lock, flags);
 	tsevq = list_first_entry(&ptp->tsevqs, struct timestamp_event_queue,
 				 qlist);
-	spin_lock_irqsave(&tsevq->lock, flags);
 	list_del(&tsevq->qlist);
-	spin_unlock_irqrestore(&tsevq->lock, flags);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 	bitmap_free(tsevq->mask);
 	kfree(tsevq);
 	debugfs_remove(ptp->debugfs_root);
@@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_lock_init(&ptp->tsevqs_lock);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;
@@ -407,6 +408,7 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 {
 	struct timestamp_event_queue *tsevq;
 	struct pps_event_time evt;
+	unsigned long flags;
 
 	switch (event->type) {
 
@@ -415,10 +417,12 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 
 	case PTP_CLOCK_EXTTS:
 		/* Enqueue timestamp on selected queues */
+		spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 		list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
 			if (test_bit((unsigned int)event->index, tsevq->mask))
 				enqueue_external_timestamp(tsevq, event);
 		}
+		spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 		wake_up_interruptible(&ptp->tsev_wq);
 		break;
 
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 52f87e394aa6..35fde0a05746 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 */
+	spinlock_t tsevqs_lock; /* protects tsevqs from concurrent access */
 	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 */
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 473b6d992507..3f7a74788802 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -588,7 +588,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 free_event:
 	kfree(event);
 exit:
-	if (result < 0)
-		ptp_release(pccontext);
 	return result;
 }
-- 
2.25.1

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

[syzbot]

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

***

Subject: [PATCH] Test for 2030579113a1
Author: eadavis@qq.com

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..473b6d992507 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -108,6 +108,7 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 		container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
+	unsigned long flags;
 
 	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
 	if (!queue)
@@ -119,7 +120,9 @@ int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 	}
 	bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
 	spin_lock_init(&queue->lock);
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 	pccontext->private_clkdata = queue;
 
 	/* Debugfs contents */
@@ -139,16 +142,16 @@ int ptp_release(struct posix_clock_context *pccontext)
 {
 	struct timestamp_event_queue *queue = pccontext->private_clkdata;
 	unsigned long flags;
+	struct ptp_clock *ptp =
+		container_of(pccontext->clk, struct ptp_clock, clock);
 
-	if (queue) {
-		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);
-		bitmap_free(queue->mask);
-		kfree(queue);
-	}
+	debugfs_remove(queue->debugfs_instance);
+	pccontext->private_clkdata = NULL;
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
+	list_del(&queue->qlist);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
+	bitmap_free(queue->mask);
+	kfree(queue);
 	return 0;
 }
 
diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
index 3d1b0a97301c..b901f2910963 100644
--- a/drivers/ptp/ptp_clock.c
+++ b/drivers/ptp/ptp_clock.c
@@ -179,11 +179,11 @@ static void ptp_clock_release(struct device *dev)
 	mutex_destroy(&ptp->pincfg_mux);
 	mutex_destroy(&ptp->n_vclocks_mux);
 	/* Delete first entry */
+	spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 	tsevq = list_first_entry(&ptp->tsevqs, struct timestamp_event_queue,
 				 qlist);
-	spin_lock_irqsave(&tsevq->lock, flags);
 	list_del(&tsevq->qlist);
-	spin_unlock_irqrestore(&tsevq->lock, flags);
+	spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 	bitmap_free(tsevq->mask);
 	kfree(tsevq);
 	debugfs_remove(ptp->debugfs_root);
@@ -247,6 +247,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 	if (!queue)
 		goto no_memory_queue;
 	list_add_tail(&queue->qlist, &ptp->tsevqs);
+	spin_lock_init(&ptp->tsevqs_lock);
 	queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
 	if (!queue->mask)
 		goto no_memory_bitmap;
@@ -407,6 +408,7 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 {
 	struct timestamp_event_queue *tsevq;
 	struct pps_event_time evt;
+	unsigned long flags;
 
 	switch (event->type) {
 
@@ -415,10 +417,12 @@ void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 
 	case PTP_CLOCK_EXTTS:
 		/* Enqueue timestamp on selected queues */
+		spin_lock_irqsave(&ptp->tsevqs_lock, flags);
 		list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
 			if (test_bit((unsigned int)event->index, tsevq->mask))
 				enqueue_external_timestamp(tsevq, event);
 		}
+		spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
 		wake_up_interruptible(&ptp->tsev_wq);
 		break;
 
diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
index 52f87e394aa6..35fde0a05746 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 */
+	spinlock_t tsevqs_lock; /* protects tsevqs from concurrent access */
 	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 */
diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index 473b6d992507..3f7a74788802 100644
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -588,7 +588,5 @@ ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 free_event:
 	kfree(event);
 exit:
-	if (result < 0)
-		ptp_release(pccontext);
 	return result;
 }
-- 
2.25.1