From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E4CEA3EDADB for ; Fri, 8 May 2026 14:22:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250180; cv=none; b=geD80KJdEfYm6vAo/4D3+KGAu17I4mCJ6FiHc6MRBlJqUbzb9Jz+I4/180S7RdveDf81JCLPqAhyXoc42SVrspts26cZGEAc3OX98Sk5MSZ8jqJxSF505Kk9qzSV4ZwARrjamyyYVzouoN23VwKETT4K1v28zkOPP9IsDiHjxr8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250180; c=relaxed/simple; bh=9GB+ziTtdeVYCQnUmC7zDEpCVCYJcbt0B5vs9CfUbGY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Ds59ER32WM+9/02qC1FTTq845AJ2V3qVMLVspR2rIu7KNineWn9v8XTiO2gZvM9Tn62tWOqhGKDcCwD4I3KMtXg02EtCtXnYfHLk1QOvRkQHYugDK95JFM40VI6eEGl09L3fjJBlV0cLRp9/hDflASHKuOPFGXVSphINHIKW9MY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a4zgkkxr; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a4zgkkxr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45093C2BCB0; Fri, 8 May 2026 14:22:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778250179; bh=9GB+ziTtdeVYCQnUmC7zDEpCVCYJcbt0B5vs9CfUbGY=; h=From:To:Cc:Subject:Date:Reply-To:From; b=a4zgkkxrHXuysTJz/HdaxnO3OLXQ8z790/nZTJeaZUh/3Y67rwC4vXmOg4+tGJ9YV UJhaRBemCXGBwvOYKMEI9bfgwWqqW+aTbouTYVbYSPjMLXwYJaF0pTK62J0UwRG4Ue tXjIRDZlUOwRMZYVlrzrkvbwWbsNilImvmYQLpFM= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43374: net: nexthop: fix percpu use-after-free in remove_nh_grp_entry Date: Fri, 8 May 2026 16:21:43 +0200 Message-ID: <2026050830-CVE-2026-43374-385e@gregkh> X-Mailer: git-send-email 2.54.0 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=2983; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=GGux4cHlsZoig869nhE8ZQ6NqPcxHMu2TJL/FpfpRrI=; b=owGbwMvMwCRo6H6F97bub03G02pJDJl/P2abqtVPM1bgNNapvlh1M8yXwXff8WoevqVHDV+f/ pRVmcfVEcvCIMjEICumyPJlG8/R/RWHFL0MbU/DzGFlAhnCwMUpABNJ2M4wv3Jai77yhw0f8800 BSc0Gy5bXbTrOsOCpuUH7UP0jj9ZH+vqd2TyDbE9Dj9+AAA= 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: net: nexthop: fix percpu use-after-free in remove_nh_grp_entry When removing a nexthop from a group, remove_nh_grp_entry() publishes the new group via rcu_assign_pointer() then immediately frees the removed entry's percpu stats with free_percpu(). However, the synchronize_net() grace period in the caller remove_nexthop_from_groups() runs after the free. RCU readers that entered before the publish still see the old group and can dereference the freed stats via nh_grp_entry_stats_inc() -> get_cpu_ptr(nhge->stats), causing a use-after-free on percpu memory. Fix by deferring the free_percpu() until after synchronize_net() in the caller. Removed entries are chained via nh_list onto a local deferred free list. After the grace period completes and all RCU readers have finished, the percpu stats are safely freed. The Linux kernel CVE team has assigned CVE-2026-43374 to this issue. Affected and fixed versions =========================== Issue introduced in 6.9 with commit f4676ea74b8549cd88dbfe2a592ce4530039e61f and fixed in 6.12.78 with commit abf4feaee6405f1441929c6ebe7a250f2cd170a7 Issue introduced in 6.9 with commit f4676ea74b8549cd88dbfe2a592ce4530039e61f and fixed in 6.18.19 with commit ab5ebab9664214ba41a7633cb4e72f128204f924 Issue introduced in 6.9 with commit f4676ea74b8549cd88dbfe2a592ce4530039e61f and fixed in 6.19.9 with commit 9e08ad731862b22a87cc55f752e16d66cdc9e231 Issue introduced in 6.9 with commit f4676ea74b8549cd88dbfe2a592ce4530039e61f and fixed in 7.0 with commit b2662e7593e94ae09b1cf7ee5f09160a3612bcb2 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-2026-43374 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: net/ipv4/nexthop.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/abf4feaee6405f1441929c6ebe7a250f2cd170a7 https://git.kernel.org/stable/c/ab5ebab9664214ba41a7633cb4e72f128204f924 https://git.kernel.org/stable/c/9e08ad731862b22a87cc55f752e16d66cdc9e231 https://git.kernel.org/stable/c/b2662e7593e94ae09b1cf7ee5f09160a3612bcb2