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 226A354146F for ; Thu, 17 Sep 2026 16:41:04 +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=1789663266; cv=none; b=kLl231Z2/OHKyYxrHDnQ4O6FdjRBtZqB3gUFxr9uKHMod0lOuzGTXO18wykkOEa7Fl7u11/3/OmeYPq+QrAnNuvvsvse/X8REUuJVxA1e2XbzErgEwqx+6zBKxSkkQKCGRlghhKhukNtLET3lH5m1F/Dp5Soy+CIjERgtxZBv+s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663266; c=relaxed/simple; bh=vC36dae0ZTV514NZkhWS00BimWis5ZHCHHotLZ01E3U=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QTpjXbRbhkcGXZ6a/LXJxJ3m68ilFNS0SvnJN6XWosfxTC1BG4cW8HheWcSodB1yp1duGBL8CTmqXW6jn+KZ3FRPXAizdW9HvZWVB/em13VPpjHUCWcvoC6gAdcNx8OsFH1A+yb1YcVjZCklGtL5ubZbC7bERymQYfMbz6qA/MU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=B5n+4C0m; 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="B5n+4C0m" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 221CD1F00899; Thu, 17 Sep 2026 16:41:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789663264; bh=VOl+GUCHDOFJrwKeQ07AGsOfjI98tmY1E1/tct4dxLE=; h=From:To:Cc:Subject:Date:Reply-To; b=B5n+4C0mMbwAB2gT9lMum6BSZehL24ESHDkROE8gRIww7knfbAnpGYtSTWZQj5HEM v6b/8CItLSYUyr6hIJW8rUNnk3qh9gS9W0VOr3VUO9HFut7wzeqlaURBbuQRBlK19x IupEWd2j9vCoHCySbIlxZiaZ+ZDp/JJwldKtXb9U= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-93182: sched/fair: Fix overflow in update_tg_cfs_runnable() Date: Thu, 17 Sep 2026 17:17:39 +0100 Message-ID: <2026091702-CVE-2026-93182-c836@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=4621; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=nntHBi0mEiEpb6IJYWiXB6lt41NlmmvFueg6zxUHGho=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlrBG5FTl4X45T9/vGjt7Y1LKrS1vVp9zaeqT+TsHjtl Soz73WMHbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjCRNEuG+blGTy96i7/xXGZ2 8dX0c1bLn65WaWFYsNM/auXcKc/fCCovkrjS9qvS/2+BKAA= 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: sched/fair: Fix overflow in update_tg_cfs_runnable() A divide-by-zero crash is observed when running hackbench: [14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+ [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0 [14697.506799] [14697.507411] __dequeue_task+0x2b4/0xc70 [14697.508677] dequeue_task_fair+0x36/0x370 [14697.509047] dequeue_task+0x101/0x2f0 [14697.509426] __schedule+0x1b1/0x1a00 [14697.510868] anon_pipe_read+0x3da/0x450 [14697.511400] vfs_read+0x361/0x390 [14697.512053] __x64_sys_read+0x19/0x30 The divide-by-zero happens here: if (scale_load_down(gcfs_rq->load.weight)) { load_sum = div_u64(gcfs_rq->avg.load_sum, scale_load_down(gcfs_rq->load.weight)); } gcfs_rq->load.weight is an insane large value and is truncated to the lower 32 bits by div_u64, which happen to be 0. Using AI for investigation, the cause is a u32 overflow in update_tg_cfs_runnable(), and flat pickup became a victim when using tg_tasks(): u32 new_sum, divider; ... new_sum = se->avg.runnable_avg * divider; <-- boom The following sequence shows how this triggers the crash: propagate_entity_load_avg() update_tg_cfs_runnable() # u32 overflow corrupts runnable_sum __update_load_avg_cfs_rq() ___update_load_avg() # computes insane runnable_avg update_tg_load_avg() # propagates to tg->runnable_avg update_cfs_group() calc_concur_shares() tg_tasks() # long-to-int truncation, negative nr reweight_entity() # corrupted se->load.weight update_load_add() # corrupted cfs_rq->load.weight propagate_entity_load_avg() update_tg_cfs_load() div_u64() # divide-by-zero Fix by widening new_sum from u32 to u64 (no need to force tg_tasks() to return unsigned long after this fix) The Linux kernel CVE team has assigned CVE-2026-93182 to this issue. Affected and fixed versions =========================== Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 6.1.188 with commit 39d707097a0820c6e87eff4195f0940e8ff1147e Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 6.6.157 with commit 69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75 Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 6.12.110 with commit 7cc237e3bc1733928313d2462b413ae441b0eef3 Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 6.18.52 with commit 18fdd0978ec3dda0ff6865cd273e47e022180710 Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 7.2.6 with commit f94e62d21faad5e244d0874598a4d0ebbc0ea405 Issue introduced in 5.17 with commit 95246d1ec80b8d19d882cd8eb7ad094e63b41bb8 and fixed in 7.3-rc1 with commit 4f166adb5cb0525d9e32d45729fd8f28c80acbee 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-2026-93182 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: kernel/sched/fair.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/39d707097a0820c6e87eff4195f0940e8ff1147e https://git.kernel.org/stable/c/69fafae4eb2c9fc9bcff1bcbfcccf5d197434d75 https://git.kernel.org/stable/c/7cc237e3bc1733928313d2462b413ae441b0eef3 https://git.kernel.org/stable/c/18fdd0978ec3dda0ff6865cd273e47e022180710 https://git.kernel.org/stable/c/f94e62d21faad5e244d0874598a4d0ebbc0ea405 https://git.kernel.org/stable/c/4f166adb5cb0525d9e32d45729fd8f28c80acbee