From 60a9bb9048f9e95029df10a9bc346f6b066c593c Mon Sep 17 00:00:00 2001 From: Ye Bin Date: Wed, 19 Oct 2022 11:36:00 +0800 Subject: blktrace: introduce 'blk_trace_{start,stop}' helper Introduce 'blk_trace_{start,stop}' helper. No functional changed. Signed-off-by: Ye Bin Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20221019033602.752383-2-yebin@huaweicloud.com Signed-off-by: Jens Axboe --- kernel/trace/blktrace.c | 74 ++++++++++++++++++++++++------------------------- 1 file changed, 36 insertions(+), 38 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 7f5eb295fe19..50b6f241b5f7 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -346,6 +346,37 @@ static void put_probe_ref(void) mutex_unlock(&blk_probe_mutex); } +static int blk_trace_start(struct blk_trace *bt) +{ + if (bt->trace_state != Blktrace_setup && + bt->trace_state != Blktrace_stopped) + return -EINVAL; + + 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; +} + +static int blk_trace_stop(struct blk_trace *bt) +{ + if (bt->trace_state != Blktrace_running) + return -EINVAL; + + 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; +} + static void blk_trace_cleanup(struct request_queue *q, struct blk_trace *bt) { synchronize_rcu(); @@ -658,7 +689,6 @@ 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 +696,10 @@ 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; + if (start) + return blk_trace_start(bt); + else + return blk_trace_stop(bt); } int blk_trace_startstop(struct request_queue *q, int start) @@ -1614,13 +1618,7 @@ 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); - } + blk_trace_stop(bt); put_probe_ref(); synchronize_rcu(); -- cgit v1.2.3 From dcd1a59c62dc49da75539213611156d6db50ab5d Mon Sep 17 00:00:00 2001 From: Ye Bin Date: Wed, 19 Oct 2022 11:36:01 +0800 Subject: blktrace: fix possible memleak in '__blk_trace_remove' 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', call 'blk_trace_cleanup' unconditionally in '__blk_trace_remove' and first stop block trace in 'blk_trace_cleanup'. Signed-off-by: Ye Bin Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20221019033602.752383-3-yebin@huaweicloud.com Signed-off-by: Jens Axboe --- kernel/trace/blktrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 50b6f241b5f7..e17bba027a2c 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -379,6 +379,7 @@ static int blk_trace_stop(struct blk_trace *bt) static void blk_trace_cleanup(struct request_queue *q, struct blk_trace *bt) { + blk_trace_stop(bt); synchronize_rcu(); blk_trace_free(q, bt); put_probe_ref(); @@ -393,8 +394,7 @@ static int __blk_trace_remove(struct request_queue *q) if (!bt) return -EINVAL; - if (bt->trace_state != Blktrace_running) - blk_trace_cleanup(q, bt); + blk_trace_cleanup(q, bt); return 0; } -- cgit v1.2.3 From 2db96217e7e515071726ca4ec791742c4202a1b2 Mon Sep 17 00:00:00 2001 From: Ye Bin Date: Wed, 19 Oct 2022 11:36:02 +0800 Subject: blktrace: remove unnessary stop block trace in 'blk_trace_shutdown' As previous commit, 'blk_trace_cleanup' 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 Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20221019033602.752383-4-yebin@huaweicloud.com Signed-off-by: Jens Axboe --- kernel/trace/blktrace.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index e17bba027a2c..a995ea1ef849 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -776,10 +776,8 @@ 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 -- cgit v1.2.3