| From bippy-1.1.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-49778: arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud |
| |
| The page table check trigger BUG_ON() unexpectedly when collapse hugepage: |
| |
| ------------[ cut here ]------------ |
| kernel BUG at mm/page_table_check.c:82! |
| Internal error: Oops - BUG: 00000000f2000800 [#1] SMP |
| Dumping ftrace buffer: |
| (ftrace buffer empty) |
| Modules linked in: |
| CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750 |
| Hardware name: linux,dummy-virt (DT) |
| pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) |
| pc : page_table_check_clear.isra.0+0x258/0x3f0 |
| lr : page_table_check_clear.isra.0+0x240/0x3f0 |
| [...] |
| Call trace: |
| page_table_check_clear.isra.0+0x258/0x3f0 |
| __page_table_check_pmd_clear+0xbc/0x108 |
| pmdp_collapse_flush+0xb0/0x160 |
| collapse_huge_page+0xa08/0x1080 |
| hpage_collapse_scan_pmd+0xf30/0x1590 |
| khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8 |
| khugepaged+0x338/0x518 |
| kthread+0x278/0x2f8 |
| ret_from_fork+0x10/0x20 |
| [...] |
| |
| Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it |
| decrease file_map_count for a non-leaf pmd comes from collapse_huge_page(). |
| and so trigger BUG_ON() unexpectedly. |
| |
| Fix this problem by using pmd_leaf() insteal of pmd_present() in |
| pmd_user_accessible_page(). Moreover, use pud_leaf() for |
| pud_user_accessible_page() too. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49778 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.19 with commit 42b2547137f5c974bb1bfd657c869fe96b96d86f and fixed in 6.0.10 with commit 2d458046df634088611d44fd77f45465e833ef78 |
| Issue introduced in 5.19 with commit 42b2547137f5c974bb1bfd657c869fe96b96d86f and fixed in 6.1 with commit 5b47348fc0b18a78c96f8474cc90b7525ad1bbfe |
| |
| 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-2022-49778 |
| 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/2d458046df634088611d44fd77f45465e833ef78 |
| https://git.kernel.org/stable/c/5b47348fc0b18a78c96f8474cc90b7525ad1bbfe |
