Linux Kernel EXT4 Deadlock Fix: EXT4_IOC_MIGRATE Race Condition

From this webpage screenshot, the following key information about the vulnerability can be obtained: 1. Vulnerability Description: - Issue Description: When the EXT4_IOC_MIGRATE ioctl is set to require synchronous updates, the file descriptor is opened in O_SYNC mode. This may cause the function to call , and if EXT4_IOC_MIGRATE competes with the system call, a deadlock may occur. - Trigger Condition: This issue only triggers when is enabled. In this case, the macro locks the , while is also locked. This causes to detect a potential deadlock because may also lock the same . - Discoverer: Discovered by the Linux Verification Center (linuxtesting.org) using syzkaller. 2. Fix Measures: - Code Change: In the function, the unlock order was changed from unlocking first and then , to unlocking first and then . - Code Diff: 3. Review and Sign-offs: - Reviewers: Ritesh Harjani (IBM), Mikhail Ukhin, Artem Sadovnikov. - Sign-offs: Mikhail Ukhin, Artem Sadovnikov, Theodore Ts'o, Sasha Levin. 4. Links: - Upstream Commit: https://lore.kernel.org/stable/20240404095000.5872-1-mish.uxin2012%40yandex.ru - Patch Link: https://patch-msgid.link/20240829152210.2754-1-ancowi69@gmail.com This information provides a detailed description of the vulnerability’s trigger conditions, impact, fix, and review process, aiding in understanding the context and remediation approach.

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Linux Kernel EXT4 Deadlock Fix: EXT4_IOC_MIGRATE Race Condition