linux-kernel - [PATCH AUTOSEL 5.8 48/72] io_uring: fix sq array offset calculation

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Date:   Sat,  8 Aug 2020 19:35:17 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Hristo Venev <hristo@...ev.name>, io-uring@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH AUTOSEL 5.8 48/72] io_uring: fix sq array offset calculation

From: Dmitry Vyukov <dvyukov@...gle.com>

[ Upstream commit b36200f543ff07a1cb346aa582349141df2c8068 ]

rings_size() sets sq_offset to the total size of the rings (the returned
value which is used for memory allocation). This is wrong: sq array should
be located within the rings, not after them. Set sq_offset to where it
should be.

Fixes: 75b28affdd6a ("io_uring: allocate the two rings together")
Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
Acked-by: Hristo Venev <hristo@...ev.name>
Cc: io-uring@...r.kernel.org
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/io_uring.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 493e5047e67c9..edb5e9d6ae3a4 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7086,6 +7086,9 @@ static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
 		return SIZE_MAX;
 #endif
 
+	if (sq_offset)
+		*sq_offset = off;
+
 	sq_array_size = array_size(sizeof(u32), sq_entries);
 	if (sq_array_size == SIZE_MAX)
 		return SIZE_MAX;
@@ -7093,9 +7096,6 @@ static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
 	if (check_add_overflow(off, sq_array_size, &off))
 		return SIZE_MAX;
 
-	if (sq_offset)
-		*sq_offset = off;
-
 	return off;
 }
 
-- 
2.25.1