Ferry Meng

**Name of the Vulnerable Software and Affected Versions** Linux kernel (affected versions not specified) **Description** The issue is related to a potential use-after-free bug in the `nilfs gccache submit read data()` function. When the `nilfs dat translate()` call fails, `brelse(bh)` is called to drop the reference count of `bh`. If the reference count hits 0 and its owner page gets unlocked, `bh` may be freed. However, `bh->b page` is dereferenced to put the page after that, which may result in a use-after-free bug. This bug can be exploited to cause a denial of service. The function in question is only called in GC, and in combination with current userland tools, address translation using DAT does not occur in that function, so the code path that causes this issue will not be executed. However, it is possible to run that code path by intentionally modifying the userland GC library or by calling the GC ioctl directly. **Recommendations** At the moment, there is no information about a newer version that contains a fix for this vulnerability.