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blktrace: move copy_[to|from]_user() out of ->debugfs_lock

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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@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-block/67450fd4.050a0220.1286eb.0007.GAE@google.com/
Closes: https://lore.kernel.org/linux-block/6742e584.050a0220.1cc393.0038.GAE@google.com/
Closes: https://lore.kernel.org/linux-block/6742a600.050a0220.1cc393.002e.GAE@google.com/
Closes: https://lore.kernel.org/linux-block/67420102.050a0220.1cc393.0019.GAE@google.com/
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241128125029.4152292-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2024-11-28 20:50:27 +08:00 committed by Jens Axboe
parent fd9b0244f5
commit b769a2f409
1 changed files with 9 additions and 17 deletions
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26
kernel/trace/blktrace.c
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@ -617,8 +617,9 @@ err:
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;
}
@ -673,12 +665,14 @@ static int compat_blk_trace_setup(struct request_queue *q, char *name,
.pid = cbuts.pid,
};
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.name, ARRAY_SIZE(buts.name))) {
__blk_trace_remove(q);
blk_trace_remove(q);
return -EFAULT;
}
@ -740,9 +734,7 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
#if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
case BLKTRACESETUP32:
snprintf(b, sizeof(b), "%pg", bdev);
mutex_lock(&q->debugfs_mutex);
ret = compat_blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
mutex_unlock(&q->debugfs_mutex);
break;
#endif
case BLKTRACESTART: