一、 漏洞 CVE-2022-49834 基础信息
漏洞信息
                                        # nilfs2：修复在重新挂载时ns_writer的use-after-free漏洞

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漏洞标题
nilfs2: fix use-after-free bug of ns_writer on remount
来源：美国国家漏洞数据库 NVD
漏洞描述信息
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix use-after-free bug of ns_writer on remount If a nilfs2 filesystem is downgraded to read-only due to metadata corruption on disk and is remounted read/write, or if emergency read-only remount is performed, detaching a log writer and synchronizing the filesystem can be done at the same time. In these cases, use-after-free of the log writer (hereinafter nilfs->ns_writer) can happen as shown in the scenario below: Task1 Task2 -------------------------------- ------------------------------ nilfs_construct_segment nilfs_segctor_sync init_wait init_waitqueue_entry add_wait_queue schedule nilfs_remount (R/W remount case) nilfs_attach_log_writer nilfs_detach_log_writer nilfs_segctor_destroy kfree finish_wait _raw_spin_lock_irqsave __raw_spin_lock_irqsave do_raw_spin_lock debug_spin_lock_before <-- use-after-free While Task1 is sleeping, nilfs->ns_writer is freed by Task2. After Task1 waked up, Task1 accesses nilfs->ns_writer which is already freed. This scenario diagram is based on the Shigeru Yoshida's post [1]. This patch fixes the issue by not detaching nilfs->ns_writer on remount so that this UAF race doesn't happen. Along with this change, this patch also inserts a few necessary read-only checks with superblock instance where only the ns_writer pointer was used to check if the filesystem is read-only.
来源：美国国家漏洞数据库 NVD
CVSS信息
N/A
来源：美国国家漏洞数据库 NVD
漏洞类别
N/A
来源：美国国家漏洞数据库 NVD
漏洞标题
Linux kernel 安全漏洞
来源：中国国家信息安全漏洞库 CNNVD
漏洞描述信息
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于nilfs2在重新挂载时释放后重用ns_writer。
来源：中国国家信息安全漏洞库 CNNVD
CVSS信息
N/A
来源：中国国家信息安全漏洞库 CNNVD
漏洞类别
其他
来源：中国国家信息安全漏洞库 CNNVD
二、漏洞 CVE-2022-49834 的公开POC
# POC 描述 源链接 神龙链接
三、漏洞 CVE-2022-49834 的情报信息