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authorDarrick J. Wong <darrick.wong@oracle.com>2019-10-15 08:44:32 -0700
committerPaul Gortmaker <paul.gortmaker@windriver.com>2020-01-31 16:51:05 -0500
commit87b234005394b7d50cabec2bf18ca671d12cf49b (patch)
treee48ab943e4225ea46f89fa4e58ddd7a444f7bb53
parentde86c841c81beb982fb87805da75e457f275186e (diff)
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splice: only read in as much information as there is pipe buffer space
commit 3253d9d093376d62b4a56e609f15d2ec5085ac73 upstream. 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> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
-rw-r--r--fs/splice.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/splice.c b/fs/splice.c
index 14cb602d9a2f..81980805de2b 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);