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 3EB7430E85B for ; Sat, 14 Feb 2026 16:05:45 +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=1771085146; cv=none; b=jB+vLel/nqQZsmqyc7PPXFe9UhV87vK2QICDBgRmR/wi98OqLeJ42NFoDcbAqg/+qUm/KD7OKBMPi4DEdeY4tL+jO+5WfYIOhvbu36Wu8awd9YJ1bITEAb5wEm0kDdNy1IqUvxwWs+yOX4Wx3FYKTIXZ/J1e9l9SRZdjF1E+SIw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771085146; c=relaxed/simple; bh=K/TcnahehGXXLpSHf6BGaN/5csexZBPEXQtuoYgn9AQ=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=QZoBdnIDkcI4QyHg4qzDT5Ps+VVHJLmwfG1JS3WsI4Y0mkIhqmxzLnmkqSlJzgZgYDNgJGx9r9zvsDgf7ZsksURhDXWyCZcRRvuW/yp7ckfA4GKuk2/VYzSmd4nFYCnxcew5xRjVGZ+Lt5L9GVXTF2MGbg5Twfz/+M2P7UKOzvg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FCpI2N83; 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="FCpI2N83" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6DE11C16AAE; Sat, 14 Feb 2026 16:05:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1771085145; bh=K/TcnahehGXXLpSHf6BGaN/5csexZBPEXQtuoYgn9AQ=; h=From:To:Cc:Subject:Date:Reply-To:From; b=FCpI2N83D5HyxGbMdJAtLtXOrq4+E2rXiyVgIz0cO/yUmeV4kbPwo+FNKu4iiOLsI wx4Gb6ah2bY7XOf1RbA6ZgFvyqiquWv4x27oJhWfHLHwgsZBQ7HE3eqO5/5PjvPm/3 XHWvZpQ27zfrNIj3vfks3nRgcrMSBssJm6lYnluc= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-23168: flex_proportions: make fprop_new_period() hardirq safe Date: Sat, 14 Feb 2026 17:04:34 +0100 Message-ID: <2026021420-CVE-2026-23168-0630@gregkh> X-Mailer: git-send-email 2.53.0 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=3399; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=cX3n+5z0CbYeCdZgZ0KBdwdLZ8LheVBdPDK6dV8bSdk=; b=owGbwMvMwCRo6H6F97bub03G02pJDJkT5rJIij++0fM2Rtd3jYSi2pN1uYzVPCfkNcVVL7u// NMu6+3fEcvCIMjEICumyPJlG8/R/RWHFL0MbU/DzGFlAhnCwMUpABPZZsIwk3GbzhWxnrS5GQb3 c86xOV/J2BDKzLBgw2Tzyi85sjar+JY9216ncj6Bp88AAA== 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: flex_proportions: make fprop_new_period() hardirq safe Bernd has reported a lockdep splat from flexible proportions code that is essentially complaining about the following race: run_timer_softirq - we are in softirq context call_timer_fn writeout_period fprop_new_period write_seqcount_begin(&p->sequence); ... blk_mq_end_request() blk_update_request() ext4_end_bio() folio_end_writeback() __wb_writeout_add() __fprop_add_percpu_max() if (unlikely(max_frac < FPROP_FRAC_BASE)) { fprop_fraction_percpu() seq = read_seqcount_begin(&p->sequence); - sees odd sequence so loops indefinitely Note that a deadlock like this is only possible if the bdi has configured maximum fraction of writeout throughput which is very rare in general but frequent for example for FUSE bdis. To fix this problem we have to make sure write section of the sequence counter is irqsafe. The Linux kernel CVE team has assigned CVE-2026-23168 to this issue. Affected and fixed versions =========================== Issue introduced in 6.0 with commit a91befde350375b1ff954635acdde14dc92cd9a8 and fixed in 6.1.162 with commit 0acc9ba7a1b5ba4d998c5753e709be904e179b75 Issue introduced in 6.0 with commit a91befde350375b1ff954635acdde14dc92cd9a8 and fixed in 6.6.123 with commit 884b2590ffcc7222cbbd6298051f4c243cc36f5d Issue introduced in 6.0 with commit a91befde350375b1ff954635acdde14dc92cd9a8 and fixed in 6.12.69 with commit 78ede9ebd679dadf480dce6f7b798e3603f88348 Issue introduced in 6.0 with commit a91befde350375b1ff954635acdde14dc92cd9a8 and fixed in 6.18.9 with commit b91a84299d72ae0e05551e851e47cd3008bd025b Issue introduced in 6.0 with commit a91befde350375b1ff954635acdde14dc92cd9a8 and fixed in 6.19 with commit dd9e2f5b38f1fdd49b1ab6d3a85f81c14369eacc 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-2026-23168 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: lib/flex_proportions.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/0acc9ba7a1b5ba4d998c5753e709be904e179b75 https://git.kernel.org/stable/c/884b2590ffcc7222cbbd6298051f4c243cc36f5d https://git.kernel.org/stable/c/78ede9ebd679dadf480dce6f7b798e3603f88348 https://git.kernel.org/stable/c/b91a84299d72ae0e05551e851e47cd3008bd025b https://git.kernel.org/stable/c/dd9e2f5b38f1fdd49b1ab6d3a85f81c14369eacc