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.

N/A
CVSS
Severity:
EPSS 0.07%
Affected: Linux Linux
Affected: Linux Linux
Published at:
Updated at:

References

Link Tags
https://git.kernel.org/stable/c/5043fbd294f5909a080ade0f04b70a4da9e122b7
https://git.kernel.org/stable/c/2e382600e8856ea654677b5134ee66e03ea72bc2
https://git.kernel.org/stable/c/6f1b228529ae49b0f85ab89bcdb6c365df401558

Frequently Asked Questions

What is the severity of CVE-2021-47493?
CVE-2021-47493 has not yet been assigned a CVSS score.
How to fix CVE-2021-47493?
To fix CVE-2021-47493, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-47493 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-47493 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-47493?
CVE-2021-47493 affects Linux Linux, Linux Linux.
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