| 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-2021-47493: ocfs2: fix race between searching chunks and release journal_head from buffer_head |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ocfs2: fix race between searching chunks and release journal_head from buffer_head |
| |
| Encountered a race between ocfs2_test_bg_bit_allocatable() and |
| jbd2_journal_put_journal_head() resulting in the below vmcore. |
| |
| PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3" |
| Call trace: |
| panic |
| oops_end |
| no_context |
| __bad_area_nosemaphore |
| bad_area_nosemaphore |
| __do_page_fault |
| do_page_fault |
| page_fault |
| [exception RIP: ocfs2_block_group_find_clear_bits+316] |
| ocfs2_block_group_find_clear_bits [ocfs2] |
| ocfs2_cluster_group_search [ocfs2] |
| ocfs2_search_chain [ocfs2] |
| ocfs2_claim_suballoc_bits [ocfs2] |
| __ocfs2_claim_clusters [ocfs2] |
| ocfs2_claim_clusters [ocfs2] |
| ocfs2_local_alloc_slide_window [ocfs2] |
| ocfs2_reserve_local_alloc_bits [ocfs2] |
| ocfs2_reserve_clusters_with_limit [ocfs2] |
| ocfs2_reserve_clusters [ocfs2] |
| ocfs2_lock_refcount_allocators [ocfs2] |
| ocfs2_make_clusters_writable [ocfs2] |
| ocfs2_replace_cow [ocfs2] |
| ocfs2_refcount_cow [ocfs2] |
| ocfs2_file_write_iter [ocfs2] |
| lo_rw_aio |
| loop_queue_work |
| kthread_worker_fn |
| kthread |
| ret_from_fork |
| |
| When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the |
| bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and |
| released the jounal head from the buffer head. Needed to take bit lock |
| for the bit 'BH_JournalHead' to fix this race. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47493 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.77 with commit 5043fbd294f5909a080ade0f04b70a4da9e122b7 |
| Fixed in 5.14.16 with commit 2e382600e8856ea654677b5134ee66e03ea72bc2 |
| Fixed in 5.15 with commit 6f1b228529ae49b0f85ab89bcdb6c365df401558 |
| |
| 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-2021-47493 |
| 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: |
| fs/ocfs2/suballoc.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/5043fbd294f5909a080ade0f04b70a4da9e122b7 |
| https://git.kernel.org/stable/c/2e382600e8856ea654677b5134ee66e03ea72bc2 |
| https://git.kernel.org/stable/c/6f1b228529ae49b0f85ab89bcdb6c365df401558 |
