From de92bc45c00b0fdde5c261e91e67c38e2d045b07 Mon Sep 17 00:00:00 2001 From: Gabriel Krisman Bertazi Date: Wed, 4 Oct 2023 20:05:29 -0400 Subject: [PATCH] io_uring/kbuf: Fix check of BID wrapping in provided buffers [ Upstream commit ab69838e7c75b0edb699c1a8f42752b30333c46f ] 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 Link: https://lore.kernel.org/r/20231005000531.30800-2-krisman@suse.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- 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 9123138..74a4f96 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; -- 2.7.4