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From: Dylan Yudaken <[email protected]>
To: <[email protected]>, <[email protected]>, <[email protected]>
Cc: <[email protected]>, Dylan Yudaken <[email protected]>
Subject: [PATCH 2/3] io_uring: fix types in provided buffer ring
Date: Mon, 13 Jun 2022 03:11:56 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

The type of head needs to match that of tail in order for rollover and
comparisons to work correctly.

Without this change the comparison of tail to head might incorrectly allow
io_uring to use a buffer that userspace had not given it.

Fixes: c7fb19428d67 ("io_uring: add support for ring mapped supplied buffers")
Signed-off-by: Dylan Yudaken <[email protected]>
---
 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 9cf9aff51b70..6eea18e8330c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -298,8 +298,8 @@ struct io_buffer_list {
 	/* below is for ring provided buffers */
 	__u16 buf_nr_pages;
 	__u16 nr_entries;
-	__u32 head;
-	__u32 mask;
+	__u16 head;
+	__u16 mask;
 };
 
 struct io_buffer {
@@ -3876,7 +3876,7 @@ static void __user *io_ring_buffer_select(struct io_kiocb *req, size_t *len,
 {
 	struct io_uring_buf_ring *br = bl->buf_ring;
 	struct io_uring_buf *buf;
-	__u32 head = bl->head;
+	__u16 head = bl->head;
 
 	if (unlikely(smp_load_acquire(&br->tail) == head)) {
 		io_ring_submit_unlock(req->ctx, issue_flags);
-- 
2.30.2


  parent reply	other threads:[~2022-06-13 10:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-13 10:11 [PATCH 0/3] io_uring: fixes for provided buffer ring Dylan Yudaken
2022-06-13 10:11 ` [PATCH 1/3] io_uring: fix index calculation Dylan Yudaken
2022-06-13 10:11 ` Dylan Yudaken [this message]
2022-06-13 10:11 ` [PATCH 3/3] io_uring: limit size of provided buffer ring Dylan Yudaken
2022-06-13 11:08 ` [PATCH 0/3] io_uring: fixes for " Hao Xu
2022-06-13 12:59   ` Pavel Begunkov
2022-06-13 13:16     ` Dylan Yudaken
2022-06-13 14:05       ` Pavel Begunkov
2022-06-14  3:47         ` Hao Xu
2022-06-13 12:49 ` Jens Axboe

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