| 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-2021-47256: mm/memory-failure: make sure wait for page writeback in memory_failure |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/memory-failure: make sure wait for page writeback in memory_failure |
| |
| Our syzkaller trigger the "BUG_ON(!list_empty(&inode->i_wb_list))" in |
| clear_inode: |
| |
| kernel BUG at fs/inode.c:519! |
| Internal error: Oops - BUG: 0 [#1] SMP |
| Modules linked in: |
| Process syz-executor.0 (pid: 249, stack limit = 0x00000000a12409d7) |
| CPU: 1 PID: 249 Comm: syz-executor.0 Not tainted 4.19.95 |
| Hardware name: linux,dummy-virt (DT) |
| pstate: 80000005 (Nzcv daif -PAN -UAO) |
| pc : clear_inode+0x280/0x2a8 |
| lr : clear_inode+0x280/0x2a8 |
| Call trace: |
| clear_inode+0x280/0x2a8 |
| ext4_clear_inode+0x38/0xe8 |
| ext4_free_inode+0x130/0xc68 |
| ext4_evict_inode+0xb20/0xcb8 |
| evict+0x1a8/0x3c0 |
| iput+0x344/0x460 |
| do_unlinkat+0x260/0x410 |
| __arm64_sys_unlinkat+0x6c/0xc0 |
| el0_svc_common+0xdc/0x3b0 |
| el0_svc_handler+0xf8/0x160 |
| el0_svc+0x10/0x218 |
| Kernel panic - not syncing: Fatal exception |
| |
| A crash dump of this problem show that someone called __munlock_pagevec |
| to clear page LRU without lock_page: do_mmap -> mmap_region -> do_munmap |
| -> munlock_vma_pages_range -> __munlock_pagevec. |
| |
| As a result memory_failure will call identify_page_state without |
| wait_on_page_writeback. And after truncate_error_page clear the mapping |
| of this page. end_page_writeback won't call sb_clear_inode_writeback to |
| clear inode->i_wb_list. That will trigger BUG_ON in clear_inode! |
| |
| Fix it by checking PageWriteback too to help determine should we skip |
| wait_on_page_writeback. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47256 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 4.14.238 with commit d05267fd27a5c4f54e06daefa3035995d765ca0c |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 4.19.196 with commit 6d210d547adc2218ef8b5bcf23518c5f2f1fd872 |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 5.4.128 with commit 566345aaabac853aa866f53a219c4b02a6beb527 |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 5.10.46 with commit 9e379da727a7a031be9b877cde7b9c34a0fb8306 |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 5.12.13 with commit 28788dc5c70597395b6b451dae4549bbaa8e2c56 |
| Issue introduced in 3.16 with commit 0bc1f8b0682caa39f45ce1e0228ebf43acb46111 and fixed in 5.13 with commit e8675d291ac007e1c636870db880f837a9ea112a |
| |
| 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-2021-47256 |
| 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/memory-failure.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/d05267fd27a5c4f54e06daefa3035995d765ca0c |
| https://git.kernel.org/stable/c/6d210d547adc2218ef8b5bcf23518c5f2f1fd872 |
| https://git.kernel.org/stable/c/566345aaabac853aa866f53a219c4b02a6beb527 |
| https://git.kernel.org/stable/c/9e379da727a7a031be9b877cde7b9c34a0fb8306 |
| https://git.kernel.org/stable/c/28788dc5c70597395b6b451dae4549bbaa8e2c56 |
| https://git.kernel.org/stable/c/e8675d291ac007e1c636870db880f837a9ea112a |
