5.15-stable review patch. If anyone has any objections, please let me know.
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From: Amir Goldstein amir73il@gmail.com
commit 724768a39374d35b70eaeae8dd87048a2ec7ae8e upstream.
ovl_{read,write}_iter() always call fdput(real) to put one or zero refcounts of the real file, but for aio, whether it was submitted or not, ovl_aio_put() also calls fdput(), which is not balanced. This is only a problem in the less common case when FDPUT_FPUT flag is set.
To fix the problem use get_file() to take file refcount and use fput() instead of fdput() in ovl_aio_put().
Fixes: 2406a307ac7d ("ovl: implement async IO routines") Cc: stable@vger.kernel.org # v5.6 Reviewed-by: Miklos Szeredi miklos@szeredi.hu Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/overlayfs/file.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-)
--- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -19,7 +19,6 @@ struct ovl_aio_req { struct kiocb iocb; refcount_t ref; struct kiocb *orig_iocb; - struct fd fd; };
static struct kmem_cache *ovl_aio_request_cachep; @@ -256,7 +255,7 @@ static rwf_t ovl_iocb_to_rwf(int ifl) static inline void ovl_aio_put(struct ovl_aio_req *aio_req) { if (refcount_dec_and_test(&aio_req->ref)) { - fdput(aio_req->fd); + fput(aio_req->iocb.ki_filp); kmem_cache_free(ovl_aio_request_cachep, aio_req); } } @@ -322,10 +321,9 @@ static ssize_t ovl_read_iter(struct kioc if (!aio_req) goto out;
- aio_req->fd = real; real.flags = 0; aio_req->orig_iocb = iocb; - kiocb_clone(&aio_req->iocb, iocb, real.file); + kiocb_clone(&aio_req->iocb, iocb, get_file(real.file)); aio_req->iocb.ki_complete = ovl_aio_rw_complete; refcount_set(&aio_req->ref, 2); ret = vfs_iocb_iter_read(real.file, &aio_req->iocb, iter); @@ -394,10 +392,9 @@ static ssize_t ovl_write_iter(struct kio /* Pacify lockdep, same trick as done in aio_write() */ __sb_writers_release(file_inode(real.file)->i_sb, SB_FREEZE_WRITE); - aio_req->fd = real; real.flags = 0; aio_req->orig_iocb = iocb; - kiocb_clone(&aio_req->iocb, iocb, real.file); + kiocb_clone(&aio_req->iocb, iocb, get_file(real.file)); aio_req->iocb.ki_flags = ifl; aio_req->iocb.ki_complete = ovl_aio_rw_complete; refcount_set(&aio_req->ref, 2);