From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 079A0426D2E; Wed, 23 Sep 2026 14:46:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790174778; cv=none; b=COJLODxns8iI8bJuUjdIZlB7o7NRpDJHsVVmEMrag7Hj7v3McqpqZ+/+0QAtMpUwZBMrXvMCUyiiplpuCe1JNkNlgxlfpeimSQY2BcJvovX0oCUBnlBCoP49/TuXW1zA8+XTOhaoVwMlqY+L/AEWW+Q+Q8re9oH10GCVVSE/PgI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790174778; c=relaxed/simple; bh=21GbXfQv8avx1q6lbO7XNYUZr5x550LWsQEMyJ0LiEU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tK47xhB1ijJHgFMBhqEqmeSdeRH0vodwnhmH7vXy4Z1fDnIlEA9XkwSuVwhIiDqMmdMDcThdhEfVFQFj9Kflv2xDMjmJz8JAiV/cSOuxJRP/rnkFYQCxL0TZPUjLI+aX75Z+AakD5vhR9BZq8h2+GBLAUgmjytqljXvRR+KrNtM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=fkTintTb; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="fkTintTb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5BCB01F000FF; Wed, 23 Sep 2026 14:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790174776; bh=islrV1ajejZ/npR3y9cPtse/6RPwDHTS3jqeKO6t0qI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fkTintTbBqYK0rn4efHRXQ9gbgFbUgKSq2IPEwBqrdBApkpTHG9gtsXOyixHa6Bzm OHtQsicPT7eAh+wdmsTNBjEIfx2ccriIi8GYEYrgCu5VkFrlurW1/8ZLF6vRZBD/S8 yQmxVlIgj1eFcPsRD22d/0yPJHazFEVYLDrfcJ8A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+a6ffe86390c8a6afc818@syzkaller.appspotmail.com, Quanye Yang , Leon Romanovsky Subject: [PATCH 6.18 222/398] RDMA/ucma: Serialize join and leave on copy_to_user failure Date: Wed, 23 Sep 2026 16:04:56 +0200 Message-ID: <20260923140649.175927471@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260923140643.441954610@linuxfoundation.org> References: <20260923140643.441954610@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Quanye Yang commit 662ade4de9ff5eceb0820a9f8e9fac70ba6a815b upstream. rdma_join_multicast() queues RoCE work that later reads the ucma_multicast through event->param.ud.private_data, then list_add()s the CMA multicast at the head of id_priv->mc_list. rdma_leave_multicast() matches only by sockaddr and destroys the first hit. ucma_process_join() used to drop ctx->mutex after a successful join and retake it only if copy_to_user() failed. Two concurrent JOIN_MCAST calls with the same address can therefore insert a second CMA entry before the first thread's leave. leave then cancels the newer work and the older worker still dereferences the ucma_multicast that the first thread frees. Keep ctx->mutex held from rdma_join_multicast() through copy_to_user() and, on -EFAULT, through rdma_leave_multicast() so leave cannot miss this join. Do not leave if join itself failed: that path never published this address on mc_list, and a leave-by-addr would destroy an earlier successful join. Reported-by: syzbot+a6ffe86390c8a6afc818@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=a6ffe86390c8a6afc818 Fixes: fe454dc31e84 ("RDMA/ucma: Fix use-after-free bug in ucma_create_uevent") Cc: stable@vger.kernel.org Signed-off-by: Quanye Yang Link: https://patch.msgid.link/20260831-rdma-ucma-mc-uaf-v1-1-b8eeb7046aff@proton.me Signed-off-by: Leon Romanovsky Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/ucma.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1556,9 +1556,10 @@ static ssize_t ucma_process_join(struct mutex_lock(&ctx->mutex); ret = rdma_join_multicast(ctx->cm_id, (struct sockaddr *)&mc->addr, join_state, mc); - mutex_unlock(&ctx->mutex); - if (ret) + if (ret) { + mutex_unlock(&ctx->mutex); goto err_xa_erase; + } resp.id = mc->id; if (copy_to_user(u64_to_user_ptr(cmd->response), @@ -1566,6 +1567,7 @@ static ssize_t ucma_process_join(struct ret = -EFAULT; goto err_leave_multicast; } + mutex_unlock(&ctx->mutex); xa_store(&multicast_table, mc->id, mc, 0); @@ -1573,7 +1575,6 @@ static ssize_t ucma_process_join(struct return 0; err_leave_multicast: - mutex_lock(&ctx->mutex); rdma_leave_multicast(ctx->cm_id, (struct sockaddr *) &mc->addr); mutex_unlock(&ctx->mutex); ucma_cleanup_mc_events(mc);