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Joseph Qi 54aa7f2330 io_uring: fix fget leak when fs don't support nowait buffered read
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 a196c78b54 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: a196c78b54 ("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>
2023-02-28 05:58:42 -07:00
arch Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
block Updates for the interrupt subsystem: 2023-02-21 10:03:48 -08:00
certs certs: don't try to update blacklist keys 2023-02-13 10:11:20 +02:00
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drivers Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
fs Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
include io_uring: rename 'in_idle' to 'in_cancel' 2023-02-22 09:57:23 -07:00
init Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
io_uring io_uring: fix fget leak when fs don't support nowait buffered read 2023-02-28 05:58:42 -07:00
ipc fs: port ->permission() to pass mnt_idmap 2023-01-19 09:24:28 +01:00
kernel Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
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LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
net Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
rust Rust changes for v6.3 2023-02-20 10:40:42 -08:00
samples samples/bpf: Use bpf_{btf,link,map,prog}_get_info_by_fd() 2023-02-16 15:32:45 -08:00
scripts Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
security This update includes the following changes: 2023-02-21 18:10:50 -08:00
sound ARM: unused boardfile removal for 6.3 2023-02-20 15:28:57 -08:00
tools Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt VFIO fixes for v6.2-rc6 2023-01-23 11:56:07 -08:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap 12 hotfixes, mostly against mm/. Five of these fixes are cc:stable. 2023-02-13 14:09:20 -08:00
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COPYING
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Makefile Rust changes for v6.3 2023-02-20 10:40:42 -08:00
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