In the Linux kernel, the following vulnerability has been resolved: dm: fix reading free memory in do_resume When do_resume calls… (CVE-2026-99036)

The Linux kernel device mapper had a race condition in the do_resume function where dm_table_get_mode(new_map) was called without holding locks, allowing a concurrent ioctl to swap the table and cause dm_table_get_mode to read freed memory. This was identified by syzbot and fixed by changing the code to read the mode before swapping the table. The vulnerability requires root privileges to trigger and is unlikely to be exploited accidentally by common tools such as lvm or cryptsetup, which do not perform concurrent ioctls.

The issue could lead to reading freed memory in the kernel, which may cause undefined behavior or kernel crashes. However, since only root can trigger the race condition and common tools do not invoke the vulnerable ioctl concurrently, the practical security impact is limited and it is not classified as a security bug.

A fix has been implemented in the Linux kernel to address this race condition by reading the mode of the new table before swapping it. Users should update to the fixed kernel version once available. No additional mitigation is necessary as the vulnerability requires root privileges and concurrent ioctl calls that are uncommon in typical usage.