6.5-stable review patch. If anyone has any objections, please let me know.
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From: Gabriel Krisman Bertazi krisman@suse.de
[ 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 krisman@suse.de Link: https://lore.kernel.org/r/20231005000531.30800-2-krisman@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7ca6f4f7819ce..427a995d26300 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -356,7 +356,7 @@ 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;