* [PATCH -next 0/3] fix possible memleak in '__blk_trace_remove'
@ 2022-10-17 6:53 Ye Bin
2022-10-17 6:53 ` [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper Ye Bin
` (2 more replies)
0 siblings, 3 replies; 7+ messages in thread
From: Ye Bin @ 2022-10-17 6:53 UTC (permalink / raw)
To: axboe, rostedt, mhiramat, linux-block; +Cc: linux-kernel, Ye Bin
Ye Bin (3):
blktrace: introduce 'blk_trace_swicth_state' helper
blktrace: fix possible memleak in '__blk_trace_remove'
blktrace: remove unnessary stop block trace in 'blk_trace_shutdown'
kernel/trace/blktrace.c | 84 ++++++++++++++++++++---------------------
1 file changed, 41 insertions(+), 43 deletions(-)
--
2.31.1
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper
2022-10-17 6:53 [PATCH -next 0/3] fix possible memleak in '__blk_trace_remove' Ye Bin
@ 2022-10-17 6:53 ` Ye Bin
2022-10-18 7:40 ` Christoph Hellwig
2022-10-17 6:53 ` [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove' Ye Bin
2022-10-17 6:53 ` [PATCH -next 3/3] blktrace: remove unnessary stop block trace in 'blk_trace_shutdown' Ye Bin
2 siblings, 1 reply; 7+ messages in thread
From: Ye Bin @ 2022-10-17 6:53 UTC (permalink / raw)
To: axboe, rostedt, mhiramat, linux-block; +Cc: linux-kernel, Ye Bin
Introduce 'blk_trace_swicth_state' helper. No functional changed.
Signed-off-by: Ye Bin <yebin10@huawei.com>
---
kernel/trace/blktrace.c | 74 ++++++++++++++++++++---------------------
1 file changed, 36 insertions(+), 38 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 7f5eb295fe19..edd83e213580 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -353,6 +353,39 @@ static void blk_trace_cleanup(struct request_queue *q, struct blk_trace *bt)
put_probe_ref();
}
+static int blk_trace_switch_state(struct blk_trace *bt, int start)
+{
+ /*
+ * For starting a trace, we can transition from a setup or stopped
+ * trace. For stopping a trace, the state must be running
+ */
+ if (start) {
+ if (bt->trace_state == Blktrace_setup ||
+ bt->trace_state == Blktrace_stopped) {
+ blktrace_seq++;
+ smp_mb();
+ bt->trace_state = Blktrace_running;
+ raw_spin_lock_irq(&running_trace_lock);
+ list_add(&bt->running_list, &running_trace_list);
+ raw_spin_unlock_irq(&running_trace_lock);
+
+ trace_note_time(bt);
+ return 0;
+ }
+ } else {
+ if (bt->trace_state == Blktrace_running) {
+ bt->trace_state = Blktrace_stopped;
+ raw_spin_lock_irq(&running_trace_lock);
+ list_del_init(&bt->running_list);
+ raw_spin_unlock_irq(&running_trace_lock);
+ relay_flush(bt->rchan);
+ return 0;
+ }
+ }
+
+ return -EINVAL;
+}
+
static int __blk_trace_remove(struct request_queue *q)
{
struct blk_trace *bt;
@@ -658,7 +691,6 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
static int __blk_trace_startstop(struct request_queue *q, int start)
{
- int ret;
struct blk_trace *bt;
bt = rcu_dereference_protected(q->blk_trace,
@@ -666,36 +698,7 @@ static int __blk_trace_startstop(struct request_queue *q, int start)
if (bt == NULL)
return -EINVAL;
- /*
- * For starting a trace, we can transition from a setup or stopped
- * trace. For stopping a trace, the state must be running
- */
- ret = -EINVAL;
- if (start) {
- if (bt->trace_state == Blktrace_setup ||
- bt->trace_state == Blktrace_stopped) {
- blktrace_seq++;
- smp_mb();
- bt->trace_state = Blktrace_running;
- raw_spin_lock_irq(&running_trace_lock);
- list_add(&bt->running_list, &running_trace_list);
- raw_spin_unlock_irq(&running_trace_lock);
-
- trace_note_time(bt);
- ret = 0;
- }
- } else {
- if (bt->trace_state == Blktrace_running) {
- bt->trace_state = Blktrace_stopped;
- raw_spin_lock_irq(&running_trace_lock);
- list_del_init(&bt->running_list);
- raw_spin_unlock_irq(&running_trace_lock);
- relay_flush(bt->rchan);
- ret = 0;
- }
- }
-
- return ret;
+ return blk_trace_switch_state(bt, start);
}
int blk_trace_startstop(struct request_queue *q, int start)
@@ -1614,13 +1617,8 @@ static int blk_trace_remove_queue(struct request_queue *q)
if (bt == NULL)
return -EINVAL;
- if (bt->trace_state == Blktrace_running) {
- bt->trace_state = Blktrace_stopped;
- raw_spin_lock_irq(&running_trace_lock);
- list_del_init(&bt->running_list);
- raw_spin_unlock_irq(&running_trace_lock);
- relay_flush(bt->rchan);
- }
+ if (bt->trace_state == Blktrace_running)
+ blk_trace_switch_state(bt, 0);
put_probe_ref();
synchronize_rcu();
--
2.31.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove'
2022-10-17 6:53 [PATCH -next 0/3] fix possible memleak in '__blk_trace_remove' Ye Bin
2022-10-17 6:53 ` [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper Ye Bin
@ 2022-10-17 6:53 ` Ye Bin
2022-10-18 7:38 ` Yu Kuai
2022-10-18 7:41 ` Christoph Hellwig
2022-10-17 6:53 ` [PATCH -next 3/3] blktrace: remove unnessary stop block trace in 'blk_trace_shutdown' Ye Bin
2 siblings, 2 replies; 7+ messages in thread
From: Ye Bin @ 2022-10-17 6:53 UTC (permalink / raw)
To: axboe, rostedt, mhiramat, linux-block; +Cc: linux-kernel, Ye Bin
When test as follows:
step1: ioctl(sda, BLKTRACESETUP, &arg)
step2: ioctl(sda, BLKTRACESTART, NULL)
step3: ioctl(sda, BLKTRACETEARDOWN, NULL)
step4: ioctl(sda, BLKTRACESETUP, &arg)
Got issue as follows:
debugfs: File 'dropped' in directory 'sda' already present!
debugfs: File 'msg' in directory 'sda' already present!
debugfs: File 'trace0' in directory 'sda' already present!
And also find syzkaller report issue like "KASAN: use-after-free Read in relay_switch_subbuf"
"https://syzkaller.appspot.com/bug?id=13849f0d9b1b818b087341691be6cc3ac6a6bfb7"
If remove block trace without stop(BLKTRACESTOP) block trace, '__blk_trace_remove'
will just set 'q->blk_trace' with NULL. However, debugfs file isn't removed, so
will report file already present when call BLKTRACESETUP.
static int __blk_trace_remove(struct request_queue *q)
{
struct blk_trace *bt;
bt = rcu_replace_pointer(q->blk_trace, NULL,
lockdep_is_held(&q->debugfs_mutex));
if (!bt)
return -EINVAL;
if (bt->trace_state != Blktrace_running)
blk_trace_cleanup(q, bt);
return 0;
}
If do test as follows:
step1: ioctl(sda, BLKTRACESETUP, &arg)
step2: ioctl(sda, BLKTRACESTART, NULL)
step3: ioctl(sda, BLKTRACETEARDOWN, NULL)
step4: remove sda
There will remove debugfs directory which will remove recursively all file
under directory.
>> blk_release_queue
>> debugfs_remove_recursive(q->debugfs_dir)
So all files which created in 'do_blk_trace_setup' are removed, and
'dentry->d_inode' is NULL. But 'q->blk_trace' is still in 'running_trace_lock',
'trace_note_tsk' will traverse 'running_trace_lock' all nodes.
>>trace_note_tsk
>> trace_note
>> relay_reserve
>> relay_switch_subbuf
>> d_inode(buf->dentry)->i_size
To solve above issues, reference commit '5afedf670caf', first stop block trace
when block trace state is 'Blktrace_running' in '__blk_trace_remove'.
Signed-off-by: Ye Bin <yebin10@huawei.com>
---
kernel/trace/blktrace.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index edd83e213580..0d93a0110ab5 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -395,8 +395,10 @@ static int __blk_trace_remove(struct request_queue *q)
if (!bt)
return -EINVAL;
- if (bt->trace_state != Blktrace_running)
- blk_trace_cleanup(q, bt);
+ if (bt->trace_state == Blktrace_running)
+ blk_trace_switch_state(bt, 0);
+
+ blk_trace_cleanup(q, bt);
return 0;
}
--
2.31.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH -next 3/3] blktrace: remove unnessary stop block trace in 'blk_trace_shutdown'
2022-10-17 6:53 [PATCH -next 0/3] fix possible memleak in '__blk_trace_remove' Ye Bin
2022-10-17 6:53 ` [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper Ye Bin
2022-10-17 6:53 ` [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove' Ye Bin
@ 2022-10-17 6:53 ` Ye Bin
2 siblings, 0 replies; 7+ messages in thread
From: Ye Bin @ 2022-10-17 6:53 UTC (permalink / raw)
To: axboe, rostedt, mhiramat, linux-block; +Cc: linux-kernel, Ye Bin
As previous commit, '__blk_trace_remove' will stop block trace if
block trace's state is 'Blktrace_running'.
So remove unnessary stop block trace in 'blk_trace_shutdown'.
Signed-off-by: Ye Bin <yebin10@huawei.com>
---
kernel/trace/blktrace.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 0d93a0110ab5..f33ec0f5750a 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -777,10 +777,8 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
void blk_trace_shutdown(struct request_queue *q)
{
if (rcu_dereference_protected(q->blk_trace,
- lockdep_is_held(&q->debugfs_mutex))) {
- __blk_trace_startstop(q, 0);
+ lockdep_is_held(&q->debugfs_mutex)))
__blk_trace_remove(q);
- }
}
#ifdef CONFIG_BLK_CGROUP
--
2.31.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove'
2022-10-17 6:53 ` [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove' Ye Bin
@ 2022-10-18 7:38 ` Yu Kuai
2022-10-18 7:41 ` Christoph Hellwig
1 sibling, 0 replies; 7+ messages in thread
From: Yu Kuai @ 2022-10-18 7:38 UTC (permalink / raw)
To: Ye Bin, axboe, rostedt, mhiramat, linux-block; +Cc: linux-kernel, yukuai (C)
Hi,
在 2022/10/17 14:53, Ye Bin 写道:
> To solve above issues, reference commit '5afedf670caf', first stop block trace
> when block trace state is 'Blktrace_running' in '__blk_trace_remove'.
Will it be much simpler if we just return -EBUSY in blk_trace_remove if
state is still running?
And similar checking in blk_trace_setup.
Thanks,
Kuai
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper
2022-10-17 6:53 ` [PATCH -next 1/3] blktrace: introduce 'blk_trace_swicth_state' helper Ye Bin
@ 2022-10-18 7:40 ` Christoph Hellwig
0 siblings, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2022-10-18 7:40 UTC (permalink / raw)
To: Ye Bin; +Cc: axboe, rostedt, mhiramat, linux-block, linux-kernel
On Mon, Oct 17, 2022 at 02:53:19PM +0800, Ye Bin wrote:
> +static int blk_trace_switch_state(struct blk_trace *bt, int start)
This is a very confusing helper. Please split it into two helpers
(e.g. blk_trace_{start,stop}) instead of the awakward int used as
boolean argument that makes it do two entirely unrelated things.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove'
2022-10-17 6:53 ` [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove' Ye Bin
2022-10-18 7:38 ` Yu Kuai
@ 2022-10-18 7:41 ` Christoph Hellwig
1 sibling, 0 replies; 7+ messages in thread
From: Christoph Hellwig @ 2022-10-18 7:41 UTC (permalink / raw)
To: Ye Bin; +Cc: axboe, rostedt, mhiramat, linux-block, linux-kernel
On Mon, Oct 17, 2022 at 02:53:20PM +0800, Ye Bin wrote:
> + if (bt->trace_state == Blktrace_running)
> + blk_trace_switch_state(bt, 0);
AFAICS blk_trace_switch_state already has that state check, so there
should be no need to duplicate it here.
I think having this call in blk_trace_cleanup itself might be a little
more obvious, too.
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-10-18 7:42 UTC | newest]
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2022-10-17 6:53 [PATCH -next 0/3] fix possible memleak in '__blk_trace_remove' Ye Bin
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2022-10-18 7:40 ` Christoph Hellwig
2022-10-17 6:53 ` [PATCH -next 2/3] blktrace: fix possible memleak in '__blk_trace_remove' Ye Bin
2022-10-18 7:38 ` Yu Kuai
2022-10-18 7:41 ` Christoph Hellwig
2022-10-17 6:53 ` [PATCH -next 3/3] blktrace: remove unnessary stop block trace in 'blk_trace_shutdown' Ye Bin
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