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 CE4774A2070 for ; Thu, 24 Sep 2026 15:29:06 +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=1790263748; cv=none; b=N82D0Y3J7wK/W2NgQ2t3hm43FPU4MB9z9mbUzIxhK011w5hAbgOSiwwG5ON4Dm3i+pjYFL3mIDAi/5t2RuQahen4KXaQIQqWTQa5Ql6OTfytr7nDvziK5UrIyCdU4blhxJufv2q/H4lmuIRLPs8rrvmNfhfvgMctpauRxTSvCkM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790263748; c=relaxed/simple; bh=6OgPfZQeqLteuwHqT7DefGNq7YtkjrZpptDH+QV314Q=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=hsdXyC6rHBYzBIasQHAwjnFGG/YxITvU+WR8SOv3Dkc1ixF9HTOl99kxCE1R6DQ3WuCVuZTzPqovrCpXIH4p5ou+cHtxllJwnEZbV5salLPfFxgBptigP6eAYk9zXo3Q6aZ5PNEp/n2AG5nmKaF5f4LnZa1/lbFUiNxZFjDRrn0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=chmDBZMu; 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="chmDBZMu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E63481F000FF; Thu, 24 Sep 2026 15:29:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790263746; bh=ryAAIQYJBnTG7sfFlEXAsrFiWd/T9aTbFcUsUtCn5ME=; h=From:To:Cc:Subject:Date:Reply-To; b=chmDBZMucxRN8SjaHMbawAIGB2ogDm3gugQ6wKcpIWYnp5/xE6dDv8QV02Aq2bqs8 x3HJR2BQ4jGT0LCwj0HZSxTfWh+FYxl2p8Of4ze6m3XSvjhnUKwv3bord+Z1c89aBS nMbHqKYOfbIIzAF+DGB09OHv/y3uOidrFopi2zW4= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-93227: mm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn Date: Thu, 24 Sep 2026 17:28:43 +0200 Message-ID: <2026092441-CVE-2026-93227-2147@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=3650; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=pmezblMcv4wqIrdZ1DlIIw6nM8dq9Z/qQ/QA7qaDbe4=; b=owGbwMvMwCRo6H6F97bub03G02pJDFlbHVcmyr76VJJXODdExedm4f9LlyM81rfsCky3eeQuV rC+SF2tI5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACbypIRhfp4cG+P/JfZ/IsXC Ju6Zuj91b+OKTob5Fff/MG35/1TrZtOhujxOT4/n1VzTAQ== 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: mm/mm_init: deferred_grow_zone(): fix out-of-range first_deferred_pfn With CONFIG_DEFERRED_STRUCT_PAGE_INIT enabled, deferred_grow_zone() initializes struct pages early in boot to satisfy an allocation. With a large CMA reservation in place, the ranges deferred_init_memmap() finds may not add up to the allocation it was asked for, and the function ends up initializing the memory map of the entire zone and still falls short. That is fine in itself: the function accounts for it and leaves the caller to decide whether it now has enough memory. However, the update of pgdat->first_deferred_pfn that tracks where uninitialized memory map starts could overflow. If the node's RAM end is not aligned on PAGES_PER_SECTION boundaries and some deferred struct pages were initialized, pgdat->first_deferred_pfn would point past the end of the node's memory. deferred_init_memmap() later picks up from pgdat->first_deferred_pfn and hits a BUG_ON(), because it expects a pfn within its node. For example, when running a kernel with CONFIG_DEFERRED_STRUCT_PAGE_INIT=y and CONFIG_CMA=y using the following qemu command line qemu-system-x86_64 -enable-kvm -m 8032M -kernel bzImage \ -append "nokaslr cma=4768M@0x100000000" the kernel panics: kernel BUG at mm/mm_init.c:2131! CPU: 3 UID: 0 PID: 36 Comm: pgdatinit0 Not tainted 7.2.0-rc6 #1 RIP: 0010:deferred_init_memmap+0x1b8/0x1c0 RAX: 0000000000236000 R13: 0000000000238000 Call Trace: kthread+0xdf/0x120 ret_from_fork+0x187/0x250 Make sure that the update of pgdta->first_deferred_pfn does not overflow when the entire zone's (and therefore node's) memory map is initialized. [rppt: massaged the changelog] The Linux kernel CVE team has assigned CVE-2026-93227 to this issue. Affected and fixed versions =========================== Issue introduced in 6.18 with commit 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 and fixed in 6.18.50 with commit 45489d4f95802903ab35799b400b346fa4e13151 Issue introduced in 6.18 with commit 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 and fixed in 7.2.4 with commit 84339578c2d6936ac3a93cd1f0bbaa3468a988f2 Issue introduced in 6.18 with commit 3acb913c9d5bd8dcf61677ccba96d349e7681cf8 and fixed in 7.3-rc1 with commit 97090500d776c3f6d08e857e3a0a7cf092999094 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-2026-93227 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: mm/mm_init.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/45489d4f95802903ab35799b400b346fa4e13151 https://git.kernel.org/stable/c/84339578c2d6936ac3a93cd1f0bbaa3468a988f2 https://git.kernel.org/stable/c/97090500d776c3f6d08e857e3a0a7cf092999094