From 8049741ac93acd3a590dac070e12571fddf0e294 Mon Sep 17 00:00:00 2001 From: Serhat Kumral Date: Thu, 6 Aug 2026 23:13:58 +0300 Subject: [PATCH] RDMA/ucma: Allow path records to exactly fit the output buffer ucma_query_path() emits a path record only when the remaining output buffer is strictly larger than struct ib_path_rec_data. A buffer sized exactly for the response header and N complete records therefore gets only N - 1 records, while resp->num_paths still advertises N. A caller sizing its buffer for a single record gets a header claiming one path and no path data at all. ucma_query_ib_service() in the same file computes the record count with a plain division and so accepts an exact fit; make ucma_query_path() behave the same way. Current librdmacm is unaffected because it always sizes the response for six records while the kernel currently reports at most two paths. Other users of the UAPI that provide an exactly sized buffer can observe the truncated response. Fixes: ac53b264b2f3 ("RDMA/ucma: Support querying when IB paths are not reversible") Signed-off-by: Serhat Kumral Link: https://patch.msgid.link/20260806201358.147478-1-serhatkumral1@gmail.com Signed-off-by: Leon Romanovsky Signed-off-by: Jason Gunthorpe --- drivers/infiniband/core/ucma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index ac29dfa69bb3..4929636f7c53 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -951,7 +951,7 @@ static ssize_t ucma_query_path(struct ucma_context *ctx, resp->num_paths = ctx->cm_id->route.num_pri_alt_paths; for (i = 0, out_len -= sizeof(*resp); - i < resp->num_paths && out_len > sizeof(struct ib_path_rec_data); + i < resp->num_paths && out_len >= sizeof(struct ib_path_rec_data); i++, out_len -= sizeof(struct ib_path_rec_data)) { struct sa_path_rec *rec = &ctx->cm_id->route.path_rec[i];