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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-10-15 18:44:32 +0300 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-10-15 18:44:32 +0300 |
| commit | 3253d9d093376d62b4a56e609f15d2ec5085ac73 (patch) | |
| tree | 0589c615a6c8228a2a8b049dc6e4ab1643bb09ad /fs | |
| parent | 4f5cafb5cb8471e54afdc9054d973535614f7675 (diff) | |
| download | linux-3253d9d093376d62b4a56e609f15d2ec5085ac73.tar.xz | |
splice: only read in as much information as there is pipe buffer space
Andreas Grünbacher reports that on the two filesystems that support
iomap directio, it's possible for splice() to return -EAGAIN (instead of
a short splice) if the pipe being written to has less space available in
its pipe buffers than the length supplied by the calling process.
Months ago we fixed splice_direct_to_actor to clamp the length of the
read request to the size of the splice pipe. Do the same to do_splice.
Fixes: 17614445576b6 ("splice: don't read more than available pipe space")
Reported-by: syzbot+3c01db6025f26530cf8d@syzkaller.appspotmail.com
Reported-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Reviewed-by: Andreas Grünbacher <andreas.gruenbacher@gmail.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/splice.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/splice.c b/fs/splice.c index 98412721f056..e509239d7e06 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -945,12 +945,13 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, WARN_ON_ONCE(pipe->nrbufs != 0); while (len) { + unsigned int pipe_pages; size_t read_len; loff_t pos = sd->pos, prev_pos = pos; /* Don't try to read more the pipe has space for. */ - read_len = min_t(size_t, len, - (pipe->buffers - pipe->nrbufs) << PAGE_SHIFT); + pipe_pages = pipe->buffers - pipe->nrbufs; + read_len = min(len, (size_t)pipe_pages << PAGE_SHIFT); ret = do_splice_to(in, &pos, pipe, read_len, flags); if (unlikely(ret <= 0)) goto out_release; @@ -1180,8 +1181,15 @@ static long do_splice(struct file *in, loff_t __user *off_in, pipe_lock(opipe); ret = wait_for_space(opipe, flags); - if (!ret) + if (!ret) { + unsigned int pipe_pages; + + /* Don't try to read more the pipe has space for. */ + pipe_pages = opipe->buffers - opipe->nrbufs; + len = min(len, (size_t)pipe_pages << PAGE_SHIFT); + ret = do_splice_to(in, &offset, opipe, len, flags); + } pipe_unlock(opipe); if (ret > 0) wakeup_pipe_readers(opipe); |