CVE-2021-47342 Information

Description

In the Linux kernel the following vulnerability has been resolved:

ext4: fix possible UAF when remounting r/o a mmp-protected file system

After commit 618f003199c6 (xt4: fix memory leak in ext4_fill_super) after the file system is remounted read-only there is a race where the kmmpd thread can exit causing sbi->s_mmp_tsk to point at freed memory which the call to ext4_stop_mmpd() can trip over.

Fix this by only allowing kmmpd() to exit when it is stopped via ext4_stop_mmpd().

Bug-Report-Link: 20210629143603.2166962-1-yebin10@huawei.com

Reference

https://git.kernel.org/stable/c/b663890d854403e566169f7e90aed5cd6ff64f6b https://git.kernel.org/stable/c/7ed572cdf11081f8f9e07abd4bea56a3f2c4edbd https://git.kernel.org/stable/c/61bb4a1c417e5b95d9edb4f887f131de32e419cb