CVE-2023-54099 — Time-of-check Time-of-use (TOCTOU) Race Condition in Linux

In the Linux kernel, the following vulnerability has been resolved: fs: Protect reconfiguration of sb read-write from racing writes The reconfigure / remount code takes a lot of effort to protect filesystem's reconfiguration code from racing writes on remounting read-only. However during remounting read-only filesystem to read-write mode userspace writes can start immediately once we clear SB_RDONLY flag. This is inconvenient for example for ext4 because we need to do some writes to the filesy…