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 6FE0E57ED84 for ; Fri, 11 Sep 2026 19:53:33 +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=1789156421; cv=none; b=TJmWJVJPBf8IoeT9AKSj4M/IctfZoDoh2NK0K1nuwjLmIARAgeqXXJX7OrzxudZEMn+YYiURR0eULfnQaFdQEEibQZJv8S4J5uIqyEMy2XIxEfg3oSe9h9z2WdQkY2n9V/GG0nEMS3QVTPJPizfKaOYPD8mou4KVSr3Pg9tHPPA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789156421; c=relaxed/simple; bh=csfJTOgxjj+IPbjuUcPNy4xFLG+GyYB8JJcjsHKdLjE=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=OkmXWrJZEZlc5QjK2F+1PMvbKHsM5hi4J+fZ91kpwcfVr+rCA5IZFjvMi0ws4qSH8PZsGyLWd06zKioAr1g579WXUkCSvC/v/3yPebL9phhiMb51GlGjvsmKLOOJcUfVvSD+raVjMYYhyE11frjDbz+53g0B5YLEmALIRAoMGI8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mz7jCaHk; 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="mz7jCaHk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4B6851F0089B; Fri, 11 Sep 2026 19:53:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789156410; bh=OjNaPEBtbnHR/7jJ/JaVk/3u0hyzTadRkU9ZZmSPE7o=; h=From:To:Cc:Subject:Date:Reply-To; b=mz7jCaHksSWd4+Mpg3gg5CURz27gvMSSHq+JFbfF5CpEWNw9jDcjcRGe053Wi5E07 bdQynFj/OPH9dHxNIWWjBmJGy9HUWTqSkg9Gwrxb8VX5PloP8hY7qCQs4ioBouILes Vft5r9b3hfgGER3jLqYt3tr5Tv+U1i5tb9tkfuwY= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89507: RDMA/ucma: Lock the handler in ucma_write_cm_event() Date: Fri, 11 Sep 2026 21:43:16 +0200 Message-ID: <2026091111-CVE-2026-89507-4a4f@gregkh> X-Mailer: git-send-email 2.55.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3473; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=PwVeZsNfpPoWhA4K4f7hCshxF6yw8mO+kyB5xj7NvDk=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlLIsMTZuW92xFoY+74c13Anto/568EJ0jzz+hQzmYNv txlF+/eEcvCIMjEICumyPJlG8/R/RWHFL0MbU/DzGFlAhnCwMUpABPR7mSYX6T8RK+x6Nxnw/OL FOS/bmNebtH1kWHB4dNaAZIX98kcFPSbpMwbMPPqLxFhAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: RDMA/ucma: Lock the handler in ucma_write_cm_event() ctx->file may only be changed under the handler lock and the xa_lock, which is what stops uevents being queued for a ctx while ucma_migrate_id() moves it to another file. The CM core takes that lock before invoking ucma_event_handler(), but the write() paths that queue uevents themselves do not. ucma_write_cm_event() re-reads ctx->file for each of its four dereferences, so ucma_migrate_id() can swap it mid-sequence: mutex_lock(&ctx->file->mut); /* file A */ list_add_tail(&uevent->list, &ctx->file->event_list); /* file B */ mutex_unlock(&ctx->file->mut); /* file B */ wake_up_interruptible(&ctx->file->poll_wait); /* file B */ The window is the mutex_lock() itself: the writer sleeps in it while the migration reassigns ctx->file. The list_add_tail() then runs on file B's event_list holding only file A's mutex: list_add corruption. prev->next should be next (ffff888101320f30), but was ffff88814a08c418. (prev=ffff88814a075c18). kernel BUG at lib/list_debug.c:32! Call Trace: ucma_write_cm_event+0x36e/0x5e0 and file A's mut is left held forever, wedging its next writer in D state. The uevent is also stranded on a list ucma_cleanup_ctx_events() will not walk, so it outlives its context. /dev/infiniband/rdma_cm is 0666 and no RDMA device is involved, so an unprivileged user reaches all of this. Take the handler lock, as ucma_cleanup_mc_events() does; ctx->cm_id is pinned by the ucma_get_ctx() reference. The Linux kernel CVE team has assigned CVE-2026-89507 to this issue. Affected and fixed versions =========================== Issue introduced in 6.18 with commit a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5 and fixed in 6.18.50 with commit 4f8bb11dd2ff365e7cff1c9964ab4607292d364e Issue introduced in 6.18 with commit a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5 and fixed in 7.2.4 with commit 0be1955040a2eceed0ecfc387fdc92305411d273 Issue introduced in 6.18 with commit a3c9d0fcd3715541bbf97da2ddde9d032e2fe6d5 and fixed in 7.3-rc1 with commit f4cc21c6a8e9d392871477f9fd98d68e5ad80272 Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-89507 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: drivers/infiniband/core/ucma.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/4f8bb11dd2ff365e7cff1c9964ab4607292d364e https://git.kernel.org/stable/c/0be1955040a2eceed0ecfc387fdc92305411d273 https://git.kernel.org/stable/c/f4cc21c6a8e9d392871477f9fd98d68e5ad80272