This is a note to let you know that I've just added the patch titled
io_uring: fix fget leak when fs don't support nowait buffered read
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-fix-fget-leak-when-fs-don-t-support-nowait-buffered-read.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 54aa7f2330b82884f4a1afce0220add6e8312f8b Mon Sep 17 00:00:00 2001
From: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Date: Tue, 28 Feb 2023 12:54:59 +0800
Subject: io_uring: fix fget leak when fs don't support nowait buffered read
From: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxx/T/#t
Fixes: a196c78b5443 ("io_uring: assign non-fixed early for async work")
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Heming Zhao <heming.zhao@xxxxxxxx>
Signed-off-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
Cc: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230228045459.13524-1-joseph.qi@xxxxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/io_uring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -1728,7 +1728,7 @@ int io_req_prep_async(struct io_kiocb *r
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;
Patches currently in stable-queue which might be from joseph.qi@xxxxxxxxxxxxxxxxx are
queue-6.2/io_uring-fix-fget-leak-when-fs-don-t-support-nowait-buffered-read.patch
