4.18-stable review patch. If anyone has any objections, please let me know.
------------------ From: Cong Wang <[email protected]> commit 5fe23f262e0548ca7f19fb79f89059a60d087d22 upstream. There is a race condition between ucma_close() and ucma_resolve_ip(): CPU0 CPU1 ucma_resolve_ip(): ucma_close(): ctx = ucma_get_ctx(file, cmd.id); list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) { mutex_lock(&mut); idr_remove(&ctx_idr, ctx->id); mutex_unlock(&mut); ... mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); rdma_destroy_id(ctx->cm_id); ... ucma_free_ctx(ctx); ret = rdma_resolve_addr(); ucma_put_ctx(ctx); Before idr_remove(), ucma_get_ctx() could still find the ctx and after rdma_destroy_id(), rdma_resolve_addr() may still access id_priv pointer. Also, ucma_put_ctx() may use ctx after ucma_free_ctx() too. ucma_close() should call ucma_put_ctx() too which tests the refcnt and waits for the last one releasing it. The similar pattern is already used by ucma_destroy_id(). Reported-and-tested-by: [email protected] Reported-by: [email protected] Cc: Jason Gunthorpe <[email protected]> Cc: Doug Ledford <[email protected]> Cc: Leon Romanovsky <[email protected]> Signed-off-by: Cong Wang <[email protected]> Reviewed-by: Leon Romanovsky <[email protected]> Signed-off-by: Doug Ledford <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/infiniband/core/ucma.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1759,6 +1759,8 @@ static int ucma_close(struct inode *inod mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); + ucma_put_ctx(ctx); + wait_for_completion(&ctx->comp); /* rdma_destroy_id ensures that no event handlers are * inflight for that id before releasing it. */
