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| author | Robert Doebbelin <robert@quobyte.com> | 2016-03-07 09:50:56 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-12 07:33:39 -0700 |
| commit | f5b07883c0c3b68c9f04f1d573949c9621ab3395 (patch) | |
| tree | 8e4524cc1e9589eddc4e7836c35a3864fe1fa7cb | |
| parent | bdb486fac4c1cc167fe9017e3fd3bc5b88090d6e (diff) | |
| download | lwn-f5b07883c0c3b68c9f04f1d573949c9621ab3395.tar.gz lwn-f5b07883c0c3b68c9f04f1d573949c9621ab3395.zip | |
fuse: do not use iocb after it may have been freed
commit 7cabc61e01a0a8b663bd2b4c982aa53048218734 upstream.
There's a race in fuse_direct_IO(), whereby is_sync_kiocb() is called on an
iocb that could have been freed if async io has already completed. The fix
in this case is simple and obvious: cache the result before starting io.
It was discovered by KASan:
kernel: ==================================================================
kernel: BUG: KASan: use after free in fuse_direct_IO+0xb1a/0xcc0 at addr ffff88036c414390
Signed-off-by: Robert Doebbelin <robert@quobyte.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: bcba24ccdc82 ("fuse: enable asynchronous processing direct IO")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/fuse/file.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index b03d253ece15..34a23df361ca 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2843,6 +2843,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) loff_t i_size; size_t count = iov_iter_count(iter); struct fuse_io_priv *io; + bool is_sync = is_sync_kiocb(iocb); pos = offset; inode = file->f_mapping->host; @@ -2882,11 +2883,11 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) * to wait on real async I/O requests, so we must submit this request * synchronously. */ - if (!is_sync_kiocb(iocb) && (offset + count > i_size) && + if (!is_sync && (offset + count > i_size) && iov_iter_rw(iter) == WRITE) io->async = false; - if (io->async && is_sync_kiocb(iocb)) + if (io->async && is_sync) io->done = &wait; if (iov_iter_rw(iter) == WRITE) { @@ -2900,7 +2901,7 @@ fuse_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) fuse_aio_complete(io, ret < 0 ? ret : 0, -1); /* we have a non-extending, async request, so return */ - if (!is_sync_kiocb(iocb)) + if (!is_sync) return -EIOCBQUEUED; wait_for_completion(&wait); |