| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-48897: arm64/mm: fix incorrect file_map_count for invalid pmd |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| arm64/mm: fix incorrect file_map_count for invalid pmd |
| |
| The page table check trigger BUG_ON() unexpectedly when split hugepage: |
| |
| ------------[ cut here ]------------ |
| kernel BUG at mm/page_table_check.c:119! |
| Internal error: Oops - BUG: 00000000f2000800 [#1] SMP |
| Dumping ftrace buffer: |
| (ftrace buffer empty) |
| Modules linked in: |
| CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748 |
| Hardware name: linux,dummy-virt (DT) |
| pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) |
| pc : page_table_check_set.isra.0+0x398/0x468 |
| lr : page_table_check_set.isra.0+0x1c0/0x468 |
| [...] |
| Call trace: |
| page_table_check_set.isra.0+0x398/0x468 |
| __page_table_check_pte_set+0x160/0x1c0 |
| __split_huge_pmd_locked+0x900/0x1648 |
| __split_huge_pmd+0x28c/0x3b8 |
| unmap_page_range+0x428/0x858 |
| unmap_single_vma+0xf4/0x1c8 |
| zap_page_range+0x2b0/0x410 |
| madvise_vma_behavior+0xc44/0xe78 |
| do_madvise+0x280/0x698 |
| __arm64_sys_madvise+0x90/0xe8 |
| invoke_syscall.constprop.0+0xdc/0x1d8 |
| do_el0_svc+0xf4/0x3f8 |
| el0_svc+0x58/0x120 |
| el0t_64_sync_handler+0xb8/0xc0 |
| el0t_64_sync+0x19c/0x1a0 |
| [...] |
| |
| On arm64, pmd_leaf() will return true even if the pmd is invalid due to |
| pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count |
| will not only decrease once but also increase once. Then in set_pte_at(), |
| the file_map_count increase again, and so trigger BUG_ON() unexpectedly. |
| |
| Add !pmd_present_invalid() check in pmd_user_accessible_page() to fix the |
| problem. |
| |
| The Linux kernel CVE team has assigned CVE-2022-48897 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.19 with commit 42b2547137f5c974bb1bfd657c869fe96b96d86f and fixed in 6.1.7 with commit 21e5eca0ac9046da9918a919bc92b7b5a78d27e7 |
| Issue introduced in 5.19 with commit 42b2547137f5c974bb1bfd657c869fe96b96d86f and fixed in 6.2 with commit 74c2f81054510d45b813548cb0a1c4ebf87cdd5f |
| |
| 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-2022-48897 |
| 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: |
| arch/arm64/include/asm/pgtable.h |
| |
| |
| 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/21e5eca0ac9046da9918a919bc92b7b5a78d27e7 |
| https://git.kernel.org/stable/c/74c2f81054510d45b813548cb0a1c4ebf87cdd5f |
