On 15/03/2018 11:08 PM, Bart Van Assche wrote: > copy_to_user() returns the number of remaining bytes. Avoid that > a larger value is returned than the number of bytes that have > been copied by returning -EFAULT if not all bytes have been copied. > > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx> > --- > drivers/md/bcache/debug.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c > index af89408befe8..376899cfcbf1 100644 > --- a/drivers/md/bcache/debug.c > +++ b/drivers/md/bcache/debug.c > @@ -175,9 +175,8 @@ static ssize_t bch_dump_read(struct file *file, char __user *buf, > struct keybuf_key *w; > unsigned bytes = min(i->bytes, size); > > - int err = copy_to_user(buf, i->buf, bytes); > - if (err) > - return err; > + if (copy_to_user(buf, i->buf, bytes)) > + return -EFAULT; > Hi Bart, I am not sure whether this change is correct. -EFAULT seems not an expected return value of read(2), while -1 is the expected return value when error occurs. Maybe if copy_to_user() returns value in (0, size], "ret + (size - err)" should be returned. An exception is when copy_to_user() returns 0 and ret is 0 too, in this situation -1 should be returned. Correct me if I am wrong. Coly Li > ret += bytes; > buf += bytes; >
