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From: Gabriel Krisman Bertazi <[email protected]>
To: [email protected]
Cc: [email protected], [email protected],
	Gabriel Krisman Bertazi <[email protected]>
Subject: [PATCH 1/3] io_uring: Fix check of BID wrapping in provided buffers
Date: Wed,  4 Oct 2023 20:05:29 -0400	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Commit 3851d25c75ed0 ("io_uring: check for rollover of buffer ID when
providing buffers") introduced a check to prevent wrapping the BID
counter when sqe->off is provided, but it's off-by-one too
restrictive, rejecting the last possible BID (65534).

i.e., the following fails with -EINVAL.

     io_uring_prep_provide_buffers(sqe, addr, size, 0xFFFF, 0, 0);

Fixes: 3851d25c75ed ("io_uring: check for rollover of buffer ID when providing buffers")
Signed-off-by: Gabriel Krisman Bertazi <[email protected]>
---
 io_uring/kbuf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 556f4df25b0f..52dba81c3f50 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -352,7 +352,7 @@ 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 > USHRT_MAX)
 		return -EINVAL;
 	p->bid = tmp;
 	return 0;
-- 
2.42.0


  reply	other threads:[~2023-10-05  0:05 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-05  0:05 [PATCH 0/3] trivial fixes and a cleanup of provided buffers Gabriel Krisman Bertazi
2023-10-05  0:05 ` Gabriel Krisman Bertazi [this message]
2023-10-05  0:05 ` [PATCH 2/3] io_uring: Allow the full buffer id space for " Gabriel Krisman Bertazi
2023-10-05  0:05 ` [PATCH 3/3] io_uring: Use slab for struct io_buffer objects Gabriel Krisman Bertazi
2023-10-05  2:18 ` [PATCH 0/3] trivial fixes and a cleanup of provided buffers Jens Axboe
2023-10-05 14:25   ` Gabriel Krisman Bertazi
2023-10-05 14:38 ` Jens Axboe

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