Race Condition Affecting kernel-rt-kvm package, versions *
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Test your applications- Snyk ID SNYK-CENTOS7-KERNELRTKVM-6326695
- published 29 Feb 2024
- disclosed 28 Feb 2024
Introduced: 28 Feb 2024
CVE-2021-46982 Open this link in a new tabHow to fix?
There is no fixed version for Centos:7 kernel-rt-kvm.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-kvm package and not the kernel-rt-kvm package as distributed by Centos.
See How to fix? for Centos:7 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
f2fs: compress: fix race condition of overwrite vs truncate
pos_fsstress testcase complains a panic as belew:
------------[ cut here ]------------ kernel BUG at fs/f2fs/compress.c:1082! invalid opcode: 0000 [#1] SMP PTI CPU: 4 PID: 2753477 Comm: kworker/u16:2 Tainted: G OE 5.12.0-rc1-custom #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Workqueue: writeback wb_workfn (flush-252:16) RIP: 0010:prepare_compress_overwrite+0x4c0/0x760 [f2fs] Call Trace: f2fs_prepare_compress_overwrite+0x5f/0x80 [f2fs] f2fs_write_cache_pages+0x468/0x8a0 [f2fs] f2fs_write_data_pages+0x2a4/0x2f0 [f2fs] do_writepages+0x38/0xc0 __writeback_single_inode+0x44/0x2a0 writeback_sb_inodes+0x223/0x4d0 __writeback_inodes_wb+0x56/0xf0 wb_writeback+0x1dd/0x290 wb_workfn+0x309/0x500 process_one_work+0x220/0x3c0 worker_thread+0x53/0x420 kthread+0x12f/0x150 ret_from_fork+0x22/0x30
The root cause is truncate() may race with overwrite as below, so that one reference count left in page can not guarantee the page attaching in mapping tree all the time, after truncation, later find_lock_page() may return NULL pointer.
- prepare_compress_overwrite
- f2fs_pagecache_get_page
- unlock_page - f2fs_setattr - truncate_setsize - truncate_inode_page - delete_from_page_cache
- find_lock_page
Fix this by avoiding referencing updated page.
References
- https://access.redhat.com/security/cve/CVE-2021-46982
- https://git.kernel.org/stable/c/5639b73fd3bc6fc8ca72e3a9ac15aacaabd7ebff
- https://git.kernel.org/stable/c/64acb100fe3beb5d20184d0ae3307235bd3555c4
- https://git.kernel.org/stable/c/936158b15e2648253afb824d252c910c496d34b5
- https://git.kernel.org/stable/c/a949dc5f2c5cfe0c910b664650f45371254c0744