From: Gabriel Krisman Bertazi <krisman@suse.de>
Date: Thu, 5 Oct 2023 00:05:30 +0000 (-0400)
Subject: io_uring/kbuf: Allow the full buffer id space for provided buffers
X-Git-Tag: v6.1.68~1004
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=32b15fef33e8cd067eb4b1bbfa5c73c967b14f93;p=platform%2Fkernel%2Flinux-starfive.git

io_uring/kbuf: Allow the full buffer id space for provided buffers

[ Upstream commit f74c746e476b9dad51448b9a9421aae72b60e25f ]

nbufs tracks the number of buffers and not the last bgid. In 16-bit, we
have 2^16 valid buffers, but the check mistakenly rejects the last
bid. Let's fix it to make the interface consistent with the
documentation.

Fixes: ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS")
Signed-off-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20231005000531.30800-3-krisman@suse.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index e45602b..57ef685 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -19,12 +19,15 @@
 
 #define BGID_ARRAY	64
 
+/* BIDs are addressed by a 16-bit field in a CQE */
+#define MAX_BIDS_PER_BGID (1 << 16)
+
 struct io_provide_buf {
 	struct file			*file;
 	__u64				addr;
 	__u32				len;
 	__u32				bgid;
-	__u16				nbufs;
+	__u32				nbufs;
 	__u16				bid;
 };
 
@@ -281,7 +284,7 @@ int io_remove_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 		return -EINVAL;
 
 	tmp = READ_ONCE(sqe->fd);
-	if (!tmp || tmp > USHRT_MAX)
+	if (!tmp || tmp > MAX_BIDS_PER_BGID)
 		return -EINVAL;
 
 	memset(p, 0, sizeof(*p));
@@ -327,7 +330,7 @@ int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		return -EINVAL;
 
 	tmp = READ_ONCE(sqe->fd);
-	if (!tmp || tmp > USHRT_MAX)
+	if (!tmp || tmp > MAX_BIDS_PER_BGID)
 		return -E2BIG;
 	p->nbufs = tmp;
 	p->addr = READ_ONCE(sqe->addr);
@@ -347,7 +350,7 @@ int io_provide_buffers_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 	tmp = READ_ONCE(sqe->off);
 	if (tmp > USHRT_MAX)
 		return -E2BIG;
-	if (tmp + p->nbufs > USHRT_MAX)
+	if (tmp + p->nbufs > MAX_BIDS_PER_BGID)
 		return -EINVAL;
 	p->bid = tmp;
 	return 0;