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 4C09778C92 for ; Wed, 7 Aug 2024 15:26:45 +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=1723044405; cv=none; b=dkf5SubTFN5v/A8FcGn3TsoSxPGuszjeoUYw65UziJ1VxdSziueMpEnCNfnATvr2ExVes4W+RLKHLPd4qwIYKhFDr2MKhyWThzwps7mUJr3ugll1MuCKb3xpjqxCBN+wGrSvQE6HfCAAP5GkELb7oEhfjzu2dM3rOYECwf3Xlpo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723044405; c=relaxed/simple; bh=abzVqcEBMGFRRMCY43YvdvApuqFZhcekOUrQhwRwytU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Ry8jNcVaKeQ0jzayC7enNSuI6wDU5fk14yStXI01t7eW0mV88KZtqSBAtDi/4I3lZXJtOxpGqWXiSvMpf/xSc/d7GG8n8lv04B6PesW2s9jALrnZapJpxIcpprV0jivEQIzahQNI+2SgkcJTHLY3YpCayBW1mucRS032ZyM0ctU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=d8evKTAY; 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="d8evKTAY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1A89C32781; Wed, 7 Aug 2024 15:26:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723044405; bh=abzVqcEBMGFRRMCY43YvdvApuqFZhcekOUrQhwRwytU=; h=From:To:Cc:Subject:Date:Reply-to:From; b=d8evKTAYDDulf8qUha1nrujYbQGbsY7WrGLwp8yvl/wC5a1eKKNg51PV+aprbt82v V/dKMq613+jQ9MG2lcHMJLcdFjV4TNiJwV+TUbCKqC8oREFbwb9vQM2Iebd8aJSCM9 mI1YGEd+nB61KyVVUQGpM1JYqWn4lYcO5qu/dwtw= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2024-42241: mm/shmem: disable PMD-sized page cache if needed Date: Wed, 7 Aug 2024 17:14:47 +0200 Message-ID: <2024080741-CVE-2024-42241-baee@gregkh> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Reply-to: , X-Developer-Signature: v=1; a=openpgp-sha256; l=4379; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=abzVqcEBMGFRRMCY43YvdvApuqFZhcekOUrQhwRwytU=; b=owGbwMvMwCRo6H6F97bub03G02pJDGmb+xOTIz8+SdDYMf17nsbLObIenBXPdH74XZvovvz3f w95u4t9HbEsDIJMDLJiiixftvEc3V9xSNHL0PY0zBxWJpAhDFycAjARBguG+UVqr9RMr6b5vKva fv5TyF9rCcfrBxgWTPvDxN3aVqvOqTjHbU7Vu8sOJX4rAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit Description =========== In the Linux kernel, the following vulnerability has been resolved: mm/shmem: disable PMD-sized page cache if needed For shmem files, it's possible that PMD-sized page cache can't be supported by xarray. For example, 512MB page cache on ARM64 when the base page size is 64KB can't be supported by xarray. It leads to errors as the following messages indicate when this sort of xarray entry is split. WARNING: CPU: 34 PID: 7578 at lib/xarray.c:1025 xas_split_alloc+0xf8/0x128 Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 \ nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject \ nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 \ ip_set rfkill nf_tables nfnetlink vfat fat virtio_balloon drm fuse xfs \ libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce virtio_net \ net_failover virtio_console virtio_blk failover dimlib virtio_mmio CPU: 34 PID: 7578 Comm: test Kdump: loaded Tainted: G W 6.10.0-rc5-gavin+ #9 Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-1.el9 05/24/2024 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : xas_split_alloc+0xf8/0x128 lr : split_huge_page_to_list_to_order+0x1c4/0x720 sp : ffff8000882af5f0 x29: ffff8000882af5f0 x28: ffff8000882af650 x27: ffff8000882af768 x26: 0000000000000cc0 x25: 000000000000000d x24: ffff00010625b858 x23: ffff8000882af650 x22: ffffffdfc0900000 x21: 0000000000000000 x20: 0000000000000000 x19: ffffffdfc0900000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000018000000000 x15: 52f8004000000000 x14: 0000e00000000000 x13: 0000000000002000 x12: 0000000000000020 x11: 52f8000000000000 x10: 52f8e1c0ffff6000 x9 : ffffbeb9619a681c x8 : 0000000000000003 x7 : 0000000000000000 x6 : ffff00010b02ddb0 x5 : ffffbeb96395e378 x4 : 0000000000000000 x3 : 0000000000000cc0 x2 : 000000000000000d x1 : 000000000000000c x0 : 0000000000000000 Call trace: xas_split_alloc+0xf8/0x128 split_huge_page_to_list_to_order+0x1c4/0x720 truncate_inode_partial_folio+0xdc/0x160 shmem_undo_range+0x2bc/0x6a8 shmem_fallocate+0x134/0x430 vfs_fallocate+0x124/0x2e8 ksys_fallocate+0x4c/0xa0 __arm64_sys_fallocate+0x24/0x38 invoke_syscall.constprop.0+0x7c/0xd8 do_el0_svc+0xb4/0xd0 el0_svc+0x44/0x1d8 el0t_64_sync_handler+0x134/0x150 el0t_64_sync+0x17c/0x180 Fix it by disabling PMD-sized page cache when HPAGE_PMD_ORDER is larger than MAX_PAGECACHE_ORDER. As Matthew Wilcox pointed, the page cache in a shmem file isn't represented by a multi-index entry and doesn't have this limitation when the xarry entry is split until commit 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache"). The Linux kernel CVE team has assigned CVE-2024-42241 to this issue. Affected and fixed versions =========================== Issue introduced in 5.17 with commit 6b24ca4a1a8d and fixed in 6.6.41 with commit 93893eacb372 Issue introduced in 5.17 with commit 6b24ca4a1a8d and fixed in 6.9.10 with commit cd25208ca9b0 Issue introduced in 5.17 with commit 6b24ca4a1a8d and fixed in 6.10 with commit 9fd154ba926b 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-2024-42241 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/shmem.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/93893eacb372b0a4a30f7de6609b08c3ba6c4fd9 https://git.kernel.org/stable/c/cd25208ca9b0097f8e079d692fc678f36fdbc3f9 https://git.kernel.org/stable/c/9fd154ba926b34c833b7bfc4c14ee2e931b3d743