[PATCH 1/4] ext4: Fix possible use-after-free with AIO
From: Jan Kara <jack@suse.cz>
Date: 2013-01-23 12:56:17
Also in:
linux-fsdevel
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2013-01-30 · Re: [PATCH 1/4] ext4: Fix possible use-after-free with AIO · Theodore Ts'o <tytso@mit.edu>
- 2013-01-29 · [PATCH 1/4] ext4: Fix possible use-after-free with AIO · Jan Kara <jack@suse.cz>
Running AIO is pinning inode in memory using file reference. Once AIO is completed using aio_complete(), file reference is put and inode can be freed from memory. So we have to be sure that calling aio_complete() is the last thing we do with the inode. CC: linux-ext4@vger.kernel.org CC: "Theodore Ts'o" <tytso@mit.edu> CC: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/inode.c | 2 +- fs/ext4/page-io.c | 9 ++++----- 2 files changed, 5 insertions(+), 6 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index cbfe13b..ba06638 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c@@ -2977,9 +2977,9 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { ext4_free_io_end(io_end); out: + inode_dio_done(inode); if (is_async) aio_complete(iocb, ret, 0); - inode_dio_done(inode); return; }
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 0016fbc..b42d04f 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c@@ -103,14 +103,13 @@ static int ext4_end_io(ext4_io_end_t *io) "(inode %lu, offset %llu, size %zd, error %d)", inode->i_ino, offset, size, ret); } - if (io->iocb) - aio_complete(io->iocb, io->result, 0); - - if (io->flag & EXT4_IO_END_DIRECT) - inode_dio_done(inode); /* Wake up anyone waiting on unwritten extent conversion */ if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten)) wake_up_all(ext4_ioend_wq(inode)); + if (io->flag & EXT4_IO_END_DIRECT) + inode_dio_done(inode); + if (io->iocb) + aio_complete(io->iocb, io->result, 0); return ret; }
--
1.7.1