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| author | Joseph Qi <joseph.qi@linux.alibaba.com> | 2023-02-28 12:54:59 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-10 09:34:04 +0100 |
| commit | 75a499fc9d66a32271e2b3e4ca71156e8ad3b484 (patch) | |
| tree | 99cc9839647942f4a440350c44c78756cbcadbed /io_uring | |
| parent | bfdd27a1eb8e7e4898c6174948a2336a0a9c008b (diff) | |
| download | linux-75a499fc9d66a32271e2b3e4ca71156e8ad3b484.tar.gz | |
io_uring: fix fget leak when fs don't support nowait buffered read
commit 54aa7f2330b82884f4a1afce0220add6e8312f8b upstream.
Heming reported a BUG when using io_uring doing link-cp on ocfs2. [1]
Do the following steps can reproduce this BUG:
mount -t ocfs2 /dev/vdc /mnt/ocfs2
cp testfile /mnt/ocfs2/
./link-cp /mnt/ocfs2/testfile /mnt/ocfs2/testfile.1
umount /mnt/ocfs2
Then umount will fail, and it outputs:
umount: /mnt/ocfs2: target is busy.
While tracing umount, it blames mnt_get_count() not return as expected.
Do a deep investigation for fget()/fput() on related code flow, I've
finally found that fget() leaks since ocfs2 doesn't support nowait
buffered read.
io_issue_sqe
|-io_assign_file // do fget() first
|-io_read
|-io_iter_do_read
|-ocfs2_file_read_iter // return -EOPNOTSUPP
|-kiocb_done
|-io_rw_done
|-__io_complete_rw_common // set REQ_F_REISSUE
|-io_resubmit_prep
|-io_req_prep_async // override req->file, leak happens
This was introduced by commit a196c78b5443 in v5.18. Fix it by don't
re-assign req->file if it has already been assigned.
[1] https://lore.kernel.org/ocfs2-devel/ab580a75-91c8-d68a-3455-40361be1bfa8@linux.alibaba.com/T/#t
Fixes: a196c78b5443 ("io_uring: assign non-fixed early for async work")
Cc: <stable@vger.kernel.org>
Reported-by: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230228045459.13524-1-joseph.qi@linux.alibaba.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'io_uring')
| -rw-r--r-- | io_uring/io_uring.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 78c677869308..ce4969d3e20d 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -1597,7 +1597,7 @@ int io_req_prep_async(struct io_kiocb *req) const struct io_op_def *def = &io_op_defs[req->opcode]; /* assign early for deferred execution for non-fixed file */ - if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE)) + if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file) req->file = io_file_get_normal(req, req->cqe.fd); if (!def->prep_async) return 0; |