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| author | Miklos Szeredi <mszeredi@redhat.com> | 2020-02-06 16:39:28 +0100 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2020-02-06 16:39:28 +0100 |
| commit | f658adeea45e430a24c7a157c3d5448925ac2038 (patch) | |
| tree | 0d177c030953383081c2521fd9b2059695beb1d0 | |
| parent | d5226fa6dbae0569ee43ecfc08bdcd6770fc4755 (diff) | |
| download | linux-f658adeea45e430a24c7a157c3d5448925ac2038.tar.gz | |
fix up iter on short count in fuse_direct_io()
fuse_direct_io() can end up advancing the iterator by more than the amount
of data read or written. This case is handled by the generic code if going
through ->direct_IO(), but not in the FOPEN_DIRECT_IO case.
Fix by reverting the extra bytes from the iterator in case of error or a
short count.
To test: install lxcfs, then the following testcase
int fd = open("/var/lib/lxcfs/proc/uptime", O_RDONLY);
sendfile(1, fd, NULL, 16777216);
sendfile(1, fd, NULL, 16777216);
will spew WARN_ON() in iov_iter_pipe().
Reported-by: Peter Geis <pgwipeout@gmail.com>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Fixes: 3c3db095b68c ("fuse: use iov_iter based generic splice helpers")
Cc: <stable@vger.kernel.org> # v5.1
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
| -rw-r--r-- | fs/fuse/file.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index ce715380143cd..695369f46f92d 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1465,6 +1465,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter, } ia = NULL; if (nres < 0) { + iov_iter_revert(iter, nbytes); err = nres; break; } @@ -1473,8 +1474,10 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter, count -= nres; res += nres; pos += nres; - if (nres != nbytes) + if (nres != nbytes) { + iov_iter_revert(iter, nbytes - nres); break; + } if (count) { max_pages = iov_iter_npages(iter, fc->max_pages); ia = fuse_io_alloc(io, max_pages); |