Op 28-11-2024 om 13:50 schreef Ming Lei:
Move copy_[to|from]_user() out of ->debugfs_lock and cut the dependency
between mm->mmap_lock and q->debugfs_lock, then we avoids lots of
lockdep false positive warning. Obviously ->debug_lock isn't needed
for copy_[to|from]_user().
The only behavior change is to call blk_trace_remove() in case of setup
failure handling by re-grabbing ->debugfs_lock, and this way is just
fine since we do cover concurrent setup() & remove().
Reported-by: syzbot+91585b36b538053343e4@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/linux-block/67450fd4.050a0220.1286eb.0007.GAE@xxxxxxxxxx/
Closes: https://lore.kernel.org/linux-block/6742e584.050a0220.1cc393.0038.GAE@xxxxxxxxxx/
Closes: https://lore.kernel.org/linux-block/6742a600.050a0220.1cc393.002e.GAE@xxxxxxxxxx/
Closes: https://lore.kernel.org/linux-block/67420102.050a0220.1cc393.0019.GAE@xxxxxxxxxx/
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
kernel/trace/blktrace.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index f01aae3a2f7b..18c81e6aa496 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -617,8 +617,9 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
return ret;
}
-static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
- struct block_device *bdev, char __user *arg)
+int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
+ struct block_device *bdev,
+ char __user *arg)
{
struct blk_user_trace_setup buts;
int ret;
@@ -627,26 +628,17 @@ static int __blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (ret)
return -EFAULT;
+ mutex_lock(&q->debugfs_mutex);
ret = do_blk_trace_setup(q, name, dev, bdev, &buts);
+ mutex_unlock(&q->debugfs_mutex);
if (ret)
return ret;
if (copy_to_user(arg, &buts, sizeof(buts))) {
- __blk_trace_remove(q);
+ blk_trace_remove(q);
return -EFAULT;
}
return 0;
-}
-
-int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
- struct block_device *bdev,
- char __user *arg)
-{
- int ret;
-
- mutex_lock(&q->debugfs_mutex);
- ret = __blk_trace_setup(q, name, dev, bdev, arg);
- mutex_unlock(&q->debugfs_mutex);
return ret;
You forgot to delete "return ret;" from function blk_trace_setup()
}
[...]
