linux-kernel - [PATCH 5.4 237/270] io_uring: set ctx sq/cq entry count earlier

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Date:   Mon, 17 Aug 2020 17:17:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Tomáš Chaloupka <chalucha@...il.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.4 237/270] io_uring: set ctx sq/cq entry count earlier

From: Jens Axboe <axboe@...nel.dk>

commit bd74048108c179cea0ff52979506164c80f29da7 upstream.

If we hit an earlier error path in io_uring_create(), then we will have
accounted memory, but not set ctx->{sq,cq}_entries yet. Then when the
ring is torn down in error, we use those values to unaccount the memory.

Ensure we set the ctx entries before we're able to hit a potential error
path.

Cc: stable@...r.kernel.org
Reported-by: Tomáš Chaloupka <chalucha@...il.com>
Tested-by: Tomáš Chaloupka <chalucha@...il.com>
Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/io_uring.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -3857,6 +3857,10 @@ static int io_allocate_scq_urings(struct
 	struct io_rings *rings;
 	size_t size, sq_array_offset;
 
+	/* make sure these are sane, as we already accounted them */
+	ctx->sq_entries = p->sq_entries;
+	ctx->cq_entries = p->cq_entries;
+
 	size = rings_size(p->sq_entries, p->cq_entries, &sq_array_offset);
 	if (size == SIZE_MAX)
 		return -EOVERFLOW;
@@ -3873,8 +3877,6 @@ static int io_allocate_scq_urings(struct
 	rings->cq_ring_entries = p->cq_entries;
 	ctx->sq_mask = rings->sq_ring_mask;
 	ctx->cq_mask = rings->cq_ring_mask;
-	ctx->sq_entries = rings->sq_ring_entries;
-	ctx->cq_entries = rings->cq_ring_entries;
 
 	size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
 	if (size == SIZE_MAX) {