This is a note to let you know that I've just added the patch titled
io_uring/rw: fix unexpected link breakage
to the 5.4-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-rw-fix-unexpected-link-breakage.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bf68b5b34311ee57ed40749a1257a30b46127556 Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Tue, 27 Sep 2022 00:44:39 +0100
Subject: io_uring/rw: fix unexpected link breakage
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
commit bf68b5b34311ee57ed40749a1257a30b46127556 upstream.
req->cqe.res is set in io_read() to the amount of bytes left to be done,
which is used to figure out whether to fail a read or not. However,
io_read() may do another without returning, and we stash the previous
value into ->bytes_done but forget to update cqe.res. Then we ask a read
to do strictly less than cqe.res but expect the return to be exactly
cqe.res.
Fix the bug by updating cqe.res for retries.
Cc: stable@xxxxxxxxxxxxxxx
Reported-and-Tested-by: Beld Zhang <beldzhang@xxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/3a1088440c7be98e5800267af922a67da0ef9f13.1664235732.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -854,6 +854,7 @@ static int io_do_iopoll(struct io_ring_c
list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
struct kiocb *kiocb = &req->rw;
+ req->cqe.res = iov_iter_count(&s->iter);
/*
* Move completed entries to our local list. If we find a
* request that requires polling, break out and complete
Patches currently in stable-queue which might be from asml.silence@xxxxxxxxx are
queue-5.4/io_uring-rw-fix-unexpected-link-breakage.patch
