path: root/fs/splice.c
diff options
authorDarrick J. Wong <darrick.wong@oracle.com>2019-10-15 08:44:32 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-10-15 08:44:32 -0700
commit3253d9d093376d62b4a56e609f15d2ec5085ac73 (patch)
tree0589c615a6c8228a2a8b049dc6e4ab1643bb09ad /fs/splice.c
parentLinux 5.4-rc3 (diff)
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/splice.c')
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,
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);
+ }
if (ret > 0)