| 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-2021-47640: powerpc/kasan: Fix early region not updated correctly |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| powerpc/kasan: Fix early region not updated correctly |
| |
| The shadow's page table is not updated when PTE_RPN_SHIFT is 24 |
| and PAGE_SHIFT is 12. It not only causes false positives but |
| also false negative as shown the following text. |
| |
| Fix it by bringing the logic of kasan_early_shadow_page_entry here. |
| |
| 1. False Positive: |
| ================================================================== |
| BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 |
| Write of size 16 at addr f57f3be0 by task swapper/0/1 |
| |
| CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 |
| Call Trace: |
| [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) |
| [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 |
| [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 |
| [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 |
| [c80d1cc0] [c03018a4] memset+0x34/0x90 |
| [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 |
| [c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570 |
| [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 |
| [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 |
| [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c |
| [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 |
| [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 |
| [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64 |
| |
| Memory state around the buggy address: |
| f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 |
| f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 |
| >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 |
| ^ |
| f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 |
| f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 |
| ================================================================== |
| |
| 2. False Negative (with KASAN tests): |
| ================================================================== |
| Before fix: |
| ok 45 - kmalloc_double_kzfree |
| # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 |
| KASAN failure expected in "((volatile char *)area)[3100]", but none occurred |
| not ok 46 - vmalloc_oob |
| not ok 1 - kasan |
| |
| ================================================================== |
| After fix: |
| ok 1 - kasan |
| |
| The Linux kernel CVE team has assigned CVE-2021-47640 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.4.189 with commit 7f19245c3647afea8c7c41f795506ef70f64b9f2 |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.10.110 with commit f39a3309393a4a484532f6ba745c6acbcfe06115 |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.15.33 with commit 5a3d8f3192a409893c57808cc935e16484df1068 |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.16.19 with commit de56beace6648065d404cd9835aa7d30e3df519d |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.17.2 with commit e3d157a4b4f4e0268c98be5b7013bf4b31234bb6 |
| Issue introduced in 5.4 with commit cbd18991e24fea2c31da3bb117c83e4a3538cd11 and fixed in 5.18 with commit dd75080aa8409ce10d50fb58981c6b59bf8707d3 |
| Issue introduced in 5.3.6 with commit 3822dd8c102d11ada9d9ed8e04cad0b347a04689 |
| |
| 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-2021-47640 |
| 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/powerpc/mm/kasan/kasan_init_32.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/7f19245c3647afea8c7c41f795506ef70f64b9f2 |
| https://git.kernel.org/stable/c/f39a3309393a4a484532f6ba745c6acbcfe06115 |
| https://git.kernel.org/stable/c/5a3d8f3192a409893c57808cc935e16484df1068 |
| https://git.kernel.org/stable/c/de56beace6648065d404cd9835aa7d30e3df519d |
| https://git.kernel.org/stable/c/e3d157a4b4f4e0268c98be5b7013bf4b31234bb6 |
| https://git.kernel.org/stable/c/dd75080aa8409ce10d50fb58981c6b59bf8707d3 |
