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ovl: fix incorrect fdput() on aio completion 

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: 2406a307ac ("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>
This commit is contained in:
Amir Goldstein 2023-08-22 20:50:59 +03:00
parent ab04830202
commit 724768a393
1 changed files with 3 additions and 6 deletions
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9
fs/overlayfs/file.c
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@ -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;
@ -280,7 +279,7 @@ 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);
}
}
@ -342,10 +341,9 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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);
@ -409,10 +407,9 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
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_flags = ifl;
aio_req->iocb.ki_complete = ovl_aio_rw_complete;
refcount_set(&aio_req->ref, 2);